The reason things are worded so badly lies in the 3.0->3.5->PF transition. See below for that! I believe chill touch is still resolvable using the RAW, though.
Chill Touch
The answer to the chill touch question lies in the rules for holding the charge:
Touch Spells and Holding the Charge: In most cases, if you don't discharge a touch spell on the round you cast it, you can hold the charge (postpone the discharge of the spell) indefinitely. You can make touch attacks round after round until the spell is discharged. If you cast another spell, the touch spell dissipates.
Most touch spells discharge after a single successful attack, but chill touch makes it clear that this isn't the case. Instead, you get one touch per level. So the quoted rule allows chill touch to be used across multiple rounds; there's no need for the spell to explicitly state it. (Though it probably should, just for clarity.)
Willing targets
The rules do explicitly state that you can't hold the charge on multiple targets, so no help there! That seems to be the simplest solution, though.
As an aside, an effect that changes the range of touch spells would "unlock" the full number of targets, so there is a technical difference between the current state and your alternate wording. :P
A little bit of history
So why are the RAW in this state? Well, I did a bit of digging, and this thread was very helpful, especially this post by Hypersmurf. (Who I remember from when I posted in the enworld rules forum far too often -- thanks Hypersmurf!)
In 3.0, you could touch 6 willing targets as a full round action, or one as a standard. There was no restriction on touching all the targets the round the spell finished -- in this context the 6 target limit played well with multi-target spells.
In 3.5, the Magic Overview section was changed: the limit of 6 was removed, but the requirement of touching the targets in a single round was added. However, the rules for touch spells in combat left the old restriction of 6 targets in place. The text here directly contradicted that of the overview section. If you assume that the wording of the overview section was what the designers intended, this would still cause no problems with touch spells targeting multiple willing creatures.
In PF, both limitations are included in the overview. I would assume that someone was trying to reconcile the contradiction mentioned in 2, without realizing that it was a holdover from an intended 3.0->3.5 shift. The result? Accidental nerfing of multi-target touch range buffs.
Likewise, the wording of chill touch has been essentially unchanged since 3.0. It's been edited a little to make the wording less clumsy, but not updated to account for the changing touch attack rules. This explains why it doesn't explicitly call out that it carries across multiple rounds.
Only If Sources Beyond the Player's Handbook Are Used
Omitted from the online sorcerer description is the following from the Player's Handbook:
[The sorcerer's] new spells can be common spells chosen from the sorcerer/wizard spell list (page 192), or they can be unusual spells that the sorcerer has gained some understanding of by study. For example, a sorcerer with a scroll or spellbook detailing an unusual sorcerer/wizard spell (one not on the sorcerer/wizard spell list in this book) could select that spell as one of his new spells for attaining a new level, provided that it is of the right spell level. (54)
Emphasis mine. Using a very hard reading of the rules as written, if the DM determines the sorcerer can gain "some understanding of [the spell cure light wounds [conj] (PH 215-6)] by study" from the scroll and the spell cure light wounds appears on the Sor/Wiz spell list in another source other than the PH, the sorcerer can add it to his spells known.
As the above is largely campaign-dependent, it needn't be a scroll. The DM determines what exactly the sorcerer can study to gain this understanding (e.g. ancient dragon scales possessing the secrets of weird magic, the corpses of magical minions, the drippings of sacred candles).
I am, however, unfamiliar with a published setting or source that adds cure spells specifically and directly to the Sor/Wiz spell list.
However, another source can totally be the DM's campaign notes. Thus, in a campaign that amends the Sor/Wiz spell list, the sorcerer could, upon understanding the spell via study, select that spell as a new spell when he reaches the next level if the spell's on the Sor/Wiz list at the appropriate level.
The DM should look askance at a player who claims his authorship of another source on a cocktail napkin amends his character's spell list, unless the source is accompanied by an appropriate bribe.
Best Answer
Targeting the same creature multiple times simultaneously with the same effect causes the creature to be affected still only once
That is, this GM would rule that just because an effect can be used one time against multiple targets doesn't mean that the same effect can instead apply multiple times against one target and yield multiple results.
While it can be technically lawyered that a spell that affects multiple creatures can, instead, affect the same creature multiple times, that notion doesn't yield positive results in actual play (i.e. you'll earn a book to the noggin not applause). And, as you can see from broaching the question here, even bringing up the idea is anathema to some.
To put this negative reaction in perspective, let me employ an analogy: a game show contestant is allowed to pick two cars. While most contestants will pick two different cars, this contestant baffles host and studio audience by picking the same car twice, technically picking two cars: this car and this car again. Although this impresses the game show's lawyers, and the sponsor's pleased at the prospect of only having to provide one vehicle, this makes for lousy ratings. Seriously, don't do this: you don't want to make Drew Carey—or the GM—angry.
That said, the spell mass cure light wounds targets "one creature/level, no two of which can be more than 30 ft. apart." However, once the caster has picked that one creature to be affected, picking that same creature likely runs afoul of of Combining Magical Effects: the creature is supposed to realize simultaneously enough the same spell's effect multiple times, something the game usually either rejects outright or accommodates grudgingly (by mandating only the most recent, most beneficial, or most detrimental effect occurs).
With that in mind, a GM could allow a lone creature to be targeted multiple times by a mass cure light wounds spell then have only the highest individual result affect the target… or even have the target affected uniquely only once, the GM mandating all creatures that the spell would've affected would've been affected equally.
Compare the spell mass cure light wounds with the spell wail of the banshee: the wail targets "one living creature/level within a 40-ft.-radius spread," and "[c]reatures closest to the point of origin are affected first." This does not mean if a Wiz20 catches but two creatures in that 40-ft.-radius spread, the wizard can force those two creatures to make 10 successful Fortitude saving throws each or die! Each affected creature instead makes 1 saving throw, and the remainder of the spell's effect is wasted. (By the way, here's a Paizo messageboard discussion about the spell wail of the banshee.)
This GM urges that unless a spell or effect says otherwise, a decision to use the spell or effect against less than than its maximum number of targets doesn't make the spell or effect's power greater against the targets the spell or effect is used against!
(I could find but this lone 2011 Paizo messageboard thread discussing the idea of picking the same target multiple times for an effect that affects multiple creatures. The topic doesn't seem to warrant serious consideration.)