1. Business license generally just covers the cost to operate and assumes some general staffing and the like, things like venue and all of that are not covered. As to vehicles, entirely up to you as to what you think is reasonable, we're not going to nitpick but depending on what you want your business to be capable of you may need to invest further if you want it to have major impacts.
2. This would be a Magic Firearm enhancement since we don't require the constant purchasing of ammunition. Ether-charged cartridges are very common in the setting.
3. You can assume general improvement is possible in the general game, Ether training is usually intended for learning new abilities. Characters will get progressively stronger naturally as the game progresses.