Is the alchemy system fully implemented, or am I failing to to figure out how to make it work for in-game reasons?

Also, is there any chance that the various poisons could be used to coat weapons? Is it even possible to script something like that?

Poisons can be used in many different ways, some poisons can only be used in food, and some can be used on weapons. Note that use of poisons on weapons is a standard Bioware thing, and that you will incur a dex save to be able to coat and not mishandle and poison yourself unless you are A) an assassin, or B) a blackguard. We have added numerous additional poisons, so find away and have fun with them. Some are pretty nasty.

Aha. That helps a bit, thanks.