Natural lycanthropes are usually born not made
The Monster Manual on Lycanthropes says
Sometimes a lycanthrope begins life as a normal humanoid or giant who subsequently contracts lycanthropy after being wounded by a lycanthrope. Such a creature is called an afflicted lycanthrope. Other lycanthropes are born as lycanthropes, and are known as natural lycanthropes. (MM 170)
Emphasis mine, but, of course, individual campaigns may vary.
Alternatively or in addition, a generous DM may allow a character to gain the template natural lycanthrope by undergoing a variant of the Ritual of Vitality (Savage Species 150).
Finally, the prestige class silverstar (Faiths and Pantheons 201-2) at level 6 gains the (presumably natural) ability Selûnite lycanthrope which says that
Upon reaching 6th level, silverstars who contract any form of lycanthropy are treated as natural lycanthropes. (202)
Whether a silverstar can pass on to its offspring this treated-as-natural lycanthropy goes unmentioned by the text. (The DM must make minor adjustments to the prestige class silverstar for compatibility with Dungeons and Dragons 3.5 anyway, so ask when he does.)
No. They need to Hit.
I think you're reading too much into wounding.
There's no reason I can think of, in terms of defined game terms, to think that wounding refers to damaging vs. hitting. In other words, the rules don't tell us to prefer one over the other. In general.
However, flip back a few pages: "Player Characters as Lycanthropes" says, in part
A humanoid hit by an attack that carries the curse of lycanthropy must succeed [on a save]... or be cursed. (MM. p.207, emphasis mine.)
There it is, as you first described: the save against cursing is part of the "Hit" clause and comes into play whenever a bite hits, even if it hits for no damage.
Some have expressed concern about what hit points represent, and whether a zero-damage hit is an injury or not. That way lies madness, I think, and we don't need to go there as Hit is a defined term.
Best Answer
Ask the DM, but probably not.
The rules for silvered weapons are somewhat specific; it seems to be that silvering for the purposes of harming creatures weak to silvered weapons is a specific process:
This specificity is consistent with the werewolf's resistance description:
The use of the word "silvered" in this description tells me that silvering a weapon is a particular, intentional process, that harming these kinds of creatures requires a level of craftsmanship not found in a sack of coin. There is also the question of "if it did work, why would people bother with getting weapons silvered?" If a sack of 50 silver pieces (5 gp) were effective against silver-weak creatures, why am I spending 100 gp to have my weapon silvered properly?
However, as is always the case with improvised weapons, it is up to the DM.
For 1000 silver pieces, I'll allow it.
The real objection outlined above is that any amount of silver coins less than 1000 creates a cost imbalance - I can get a functional silver weapon for less than the rules say such a weapon should cost. However, if there's 1000 coins in that sock, then that imbalance is eliminated. Initially, I thought to myself, "1000 coins would weigh too much", but of all the things D&D 5e lacks rules for, coinage weight is not one of them:
So you're looking at a 20 pound sock, well within a strong character's ability to swing around dangerously. So for no less than 1000 coins, I'll give you a silvered weapon dealing 1d4 damage on a hit, per the rules for Improvised Weapons: