Whew! That's a lot of questions in a small amount of space. I cannot answer all of them, but let me get a few.
No matter what browser you decide to use, you must keep Internet Explorer installed. It is very much tied up with the OS and you must use IE in order to do system updates.
As for which is faster, that really depends on your situation. The only way to find out is to try them.
I am currently using IE 8 but lags alot of the time
It is possible that this is related to the infection you have posted about here: http://www.bleepingcomputer.com/forums/t/238872/hijackthis-log-and-rootrepeal-report-scan/
Once you have been declared clean of the infection and you are still experiencing lagging with IE8, I would suggest starting a fresh topic and ask only about that in the topic to avoid confusion.
also should i run a firewall or is my windows firewall fine?
A third party firewall is better because you can control outgoing traffic not just incoming. The windows firewall only blocks incoming. Once you have decided on a firewall and if you have questions about running it, I would suggest starting a new topic in this forum: http://www.bleepingcomputer.com/forums/f/25/antivirus-firewall-and-privacy-products-and-protection-methods/
and ask only about the firewall, again to avoid confusion. Please note that a firewall that works great on one person's computer may not work well on another. It may take some experimentation before you find one that works well in your situation.
Having said that, please hold off on installing one until your HiJack This topic is resolved as you should NOT make further changes to your computer
(install/uninstall programs, use special fix tools, delete files, edit the registry, etc) unless advised by a HJT Team member, nor should you ask for help elsewhere. Doing so can result in system changes which may not show in the log you already posted. Further, any modifications you make on your own may cause confusion for the helper assisting you and could complicate the malware removal process which would extend the time it takes to clean your computer.
From this point on the HJT Team should be the only members that you take advice from, until they have verified your log as clean.Please be patient. It may take a while to get a response because the HJT Team members are EXTREMELY busy working logs posted before yours. They are volunteers who will help you out as soon as possible. Once you have made your post and are waiting, please DO NOT make another reply until it has been responded to by a member of the HJT Team. Generally the staff checks the forum for postings that have 0 replies as this makes it easier for them to identify those who have not been helped. If you post another response there will be 1 reply. A team member, looking for a new log to work may assume another HJT Team member is already assisting you and not open the thread to respond. Please be patient
. It may take a while to get a response but your log will be reviewed and answered as soon as possible
To avoid confusion, I am closing this topic. Good luck with your log.