Answers:
IE 7.0 lets you do that.
I know Mozilla lets you do it. I dont know about firefox though. You might want to go to their website and look for any FAQs that might pertain to that.
maybe
Yes, it is possible for u to open up Mozilla Firefox in a new window to open ur default home page...and u can have Internet Explorer opened at tha same time...u can have multiple windows open of each browser.