No, damage reduction still applies

What they are referring to is the fact that precision damage now affects constructs, plants, and undead creatures now; in 3.5 those types were immune. In Pathfinder, only elementals and oozes are immune to precision damage.

Precision damage is of the same type as the attack to which it is applied. The only exception to this that I am aware of is attacks that deal ability damage or drain, or energy drain. In 3.5, precision damage that triggered on such attacks was dealt as Negative Energy damage. I don’t know if Pathfinder has explicitly addressed that case, but for sanity’s sake I strongly recommend all DM’s use that rule or something like it.

For the sake of citation, the rules say the following:

The rogue's attack deals extra damage anytime

That is, Sneak Attack provides a bonus to your damage roll. As a bonus to a roll, it’s just a number that gets added on to your overall damage. It does not change the attack’s damage type, it simply increases the amount of damage of that type that you do. The term “precision damage” is not a damage type, like “slashing damage,” but rather a category that certain sorts of damage bonuses go in. In this manner, it is similar to non-lethal damage.

Note: The statement that Sneak Attack may be used more frequently is perhaps misleading

That’s not really the effect that Pathfinder’s changes had: they allow Sneak Attack to be used more broadly, but there are a number of changes in Pathfinder that make it much more difficult to accomplish multiple Sneak Attacks in one round. Unfortunately, the rogue needs to do so if he is to pose much combat threat, so this is a serious problem.

The weapon special ability ghost touch doesn't allow the wielder to make incorporeal touch attacks

That last sentence isn't the extent of the description. In its entirety, the weapon special ability ghost touch says

A ghost touch weapon deals damage normally against incorporeal creatures, regardless of its bonus. (An incorporeal creature’s 50% chance to avoid damage does not apply to attacks with ghost touch weapons.) The weapon can be picked up and moved by an incorporeal creature at any time. A manifesting ghost can wield the weapon against corporeal foes. Essentially, a ghost touch weapon counts as either corporeal or incorporeal at any given time, whichever is more beneficial to the wielder. (DMG 224-5)

When the text says, "Essentially, a ghost touch weapon counts as either corporeal or incorporeal at any given time, whichever is more beneficial to the wielder," the text is clarifying, providing the reader with a summary of the weapon's fundamental functions that have already been described. It means the weapon strikes foes despite their corporeal states and the wielder can continue to use the weapon despite the wielder's corporeal state. Nothing more.

As you've noted, taking that last sentence out of context makes the weapon special ability ghost touch way more powerful than it should be for its +1 bonus.

The weapon by that sentence isn't given additional properties beyond what's already been described.

The MM and DMG agree that an incorporeal creature's physical attacks (whether with a ghost touch weapon or not) ignore non-ghost touch or non-force material armor

In addition to the Monster Manual's description of the subtype incorporeal (310-1), the Dungeon Master's Guide on Incorporeality says that

The physical attacks of incorporeal creatures ignore material armor, even magic armor, unless it is made of force (such as mage armor or bracers of armor) or has the ghost touch ability. (DMG 295)

So, while it's a little weird that a ghost (or an unbodied) can pick up from the floor a +1 ghost touch longsword and, bypassing the dude's full plate, stab the dude to death with that sword, that appears to be how it works. But were that sword not to have the weapon special ability ghost touch, the ghost would just look at the sword on the floor with despair. Okay, even more despair ('cause it's a ghost).