1/ We have not been using Dodge. A: It is against RAW - Dodge only allows you to dodge missile weapon attacks and these are equipment, not missile weapons. B: Dodging a grenade is kinda silly. I don't think moving a step or two to the side would make a lot of difference how badly you were hit.
2. There is no FAQ anywhere that I am aware of. In Mordheim everything is assumed to not be exhausted unless the rules say they are. Anything that only lasts for one battle and is then gone is very clearly said so. "there is enough for just one use", "There is enough to supply the warband for one battle only", "In either case, the net is lost" etc. Very unambiguous. Whereas flash-powder just says "one use during the battle", nothing about it being only one battle or just that battle or anything like that. Also, look at the pricing of it. Caltrops are better and cheaper by almost *half* whereas Hunting arrows are replenished, Healing Herbs are replenished, and Flash Powder is replenished and all of these are in the 20-30 gold bracket whereas one-shot-wonders are in the 5-15 bracket, heck they are as cheap as 1 gold if you include garlic.
I think the most telling thing though, is the fact that even with its replenishing, it is still not something you buy and put on every heroes - it just isn't that good. Depending on the warband people will usually buy 1-3 at the most and generally put them only on those that really need it and even then they are generally lower on the list to buy than a lot of other stuff. I think if we ruled that flash-powder was a one use ever item we would stop getting it at all.
As a matter of fact, just recently we realised that it said that only *poisons* were one-use and not drugs too so we are thinking of experimenting with what happens when you make drugs replenishable as well. It should be good because at the moment, noone buys them ever.