I recommend that you refer to the Sharing Projects and Project Suites Among Several Testers article to learn how to organize teamwork.
As for using different browsers, tests recorded with IE 8 cannot run on IE 7 as is. To learn how to make your tests browser-independent, see the following SQAforums thread:
I have the login script in one of my projects in the shared drive.
it is highlighting little above to the actual submit tab