There are lots of good SIB brands around. If you intend using it as more than a shore tender then I'd suggest avoiding the entry level offerings and go with a "brand", even if it is used. You could add Avon, Zodiac and Mercury Quicksilver to that list - there are many more.
If you plan to deploy the kit from a car (as I do) then you'll have to keep it compact. Airdeck SIBs are handy to roll up and inflate but there is some loss of performance. If you don't intend to push the speed, then this is no big issue. A 2 stroke engine will be lighter and easier to transport (they can lie on their sides as they have no oil sump). A good pump makes setting up a pleasure.
Be aware that there is a change in SIBs once they clear the 3m size - they tend jump tube sizes and become better for slightly choppier water. I guess what I'm saying is that the sub 3m SIBs are basically toys/tenders, although I've had quite a bit of fun with mine
10hp will suit most airdecks up to around 3.6m
Again I'd say - spend the big money on the engine, not the "shiny bits" on a new SIB.