As for the heat in July... get ready! I'll pray for you that it's not too bad when you're there but you commented you didn't know what the dry heat feels like. Well, imagine stepping behind the back of city bus and the exhaust hits you. That's kinda like what it's like when you leave an a/c building or casino and step outside - the heat "hits" you like the exhaust of a bus. That's the best way I can describe it.
When you're on the strip walking around, be aware that everything is at least twice as far as you perceive it to be. The casinos are HUGE so your perception is skewed. You see where you want to go and think it's not that far then you start walking and walking and walking and thought, WTH it looked like it was only a couple blocks away.
In the summer, there will be people all over the sidewalks selling cold bottles of water out of coolers. Take them up on this. Always have a bottle in your hand and drink often. Even if you don't think you need to. That dry heat takes a toll on the body.
As for tickets... DO NOT buy anything ahead of time. There are a couple places on the strip and I wish I could remember exactly where they are located (if I think of it I'll let you know) that sell day-of tickets for half price. You will not find better prices anywhere. It's set up like your buying tickets at a movie theatre... they have the lighted board with all the different shows available and then you stand in line just like at a movie theatre and buy them from the person at the window. So you have to go the day of the show but you will get the best prices.
Also, last time I was there as I was walking into Treasure Island there was a girl standing at the entrance handing out 2-4-1 passes to the Cirque du Soleil show there. VERY hard to get discount tickets to the good Cirque shows! I happened to luck out and be in the right place at the right time. Chatted her up a bit and she ended up giving me 2-4-1 to two different Cirque shows. They were both fantastic!
I had bought tickets online before I went there to another show that I thought was a good deal when I bought them. Until I got there and realized you can get much better deals once you're there. Then once I discovered the day-of 1/2 price ticket place, I'll never pre-buy anything again.
Have fun. Stay hydrated. And pray it isn't 120 degrees when you're there.