Mac getting very hot while watching flash
Flash has many problems, including making your computer run hot.  I have an older dual quad core i7 iMac, and Flash does that to my computer too.  It's also a large security hole.

I'd recommend removing flash completely, and when you need to run it, do so using Google Chrome.  Chrome has a sandboxed, often updated version of Flash. It won't solve the issue with it taxing your system, but it is a bit more secure.  

To answer your questions at the end:
1 - Chrome works fine - Flash is the problem.
2 - For Flash, I'd say use Chrome only, and leave Safari out of this.
3 - Chrome provided Flash is probably your best bet
4 - I avoid Flash as much as possible, but I do love me some Google Street View.  Gotta use Flash for it.

Good luck.