I wouldn't worry about the scare stories about going to Orlando in July, they are all exaggerated!
We went every summer in July or sometimes August for years, and were never put off!
It does get hot yes, in summer, but we never found it too hot, never that much hotter than summer holidays in Spain, Greece etc, and the heat is a more humid heat with moisture in the air.
Also, everywhere is air conditioned, so if you feel too hot, pop into a shop for a minute!
We did get a few thunderstorms but not every day, and they don't last long, and as someone said on here recently, they aren't cold and are actually very refreshing! Just buy a poncho and wear it for a while during the shower!
The queues can be bad, but if you read up on how to beat them it won't be a problem (do the parks on the least busy days, which vary for each of them so you can work round this easily), arrive early and do the biggest rides first or use fast passes for them, and use the busiest times of day to do the big shows which have a much higher capacity!
Plus the disney and universal people have made loads of things to do and see in the queueing areas (pre-shows, entertainment etc) and we found that on the times we skipped the queues completely, we missed some of the pre-amble to the ride/show which would have been useful to know! The queues also move constantly so you are never standing still in the queueing area, and I don't think we have ever queued more than about 20 minutes for anything!
Don't let scare stories put you off, talking from (years of) experience, you will still have a fantastic time in July!