July/August - yes temperature will be very hot - we are going on 25th July due to DS1 being in yr 6. This year we went May/June temp excellent, last year we went 10th July and it was hot and humid. Just make sure you drink plenty.
No age really too young as there is something for everyone 0 - 100.
Would not rent a villa - we always stay at the Sheraton Vistana Villages - fabulous - we originally stayed first time through Virgin - we now do everything ourselves. We have a 2 bed apartment with a full kitchen so on the days we don't feel like doing anything we can just go to the fridge and get what we want.
Yes I would strongly advise getting a car - I do the driving and DH does the navigating - works a treat.
I would do day at the park, day at wherever you are staying, you will not be able to do 5 consecutive days at parks it will be too much. This year, we had our middle weekend at Clearwater and the time before that we did Cocoa Beach. Both lovely. It just breaks up your holiday and gives you that extra r and r.
Always fly Virgin they are the best.
At the moment, Universal Studios and Islands of Adventure (which are two parks next to each other) have an offer on - buy two days and get 3rd free which is very good. Always do fast passes.
If you want to go on a grown up ride - a lot of them do parent swap or single rider which takes a big chunk out of having to queue.
Yes food is very cheap. We do not take toiletries or anything and just do a full shop when we get there at Publix. (Virgin supply toothbrushes and toothpaste on your flight so this will put you on) and where we stay they supply little bottles of shampoo, body lotion, shower gel etc.