Hmmm. Difficult one as I haven't really had the problems you seem to have had.
I owned an HTC Desire and now an S2. neither phone had issues getting hot or crashing/rebooting. The ONLY time the phones DO get hot is when I use them as a Sat Nav (GPS) in the car. I run it from a USB adaptor rated at 1Amp and the phone AND adaptor do tend to get hot after a while.
As for apps, I have had issues with a couple of apps, more not working properly than crashing. I have over 60 apps on my phone and everything just seems to work fine. I did have an issue where the phone crashed a couple of times after upgrading to ICS, but after a full wipe and reinstall of everything it has been fine since. I got my S2 in July, and as best as I can remember I don't think I've had a crash for 3 months now.