For MSN Messenger you can install RTComm like qole said. I did, and I love it but I had some really rough times getting it installed and some things changed before MSN would work.
But you could just install Pidgin from your application manager and put your MSN account in. it is quick and easy. Thats what I was using before RTcomm. Pidgin will give you email arrival notifications not just IMs.

from what I understand hotmail won't let any other email client pull emails. What I did in my hotmail account is set up a "forward all mail" to my Gmail account (I know you may not like Gmail) but at least I get email notifications on the tablet (blue LED)on the go and can read then with out the browser. It will leave a copy of the email in your hotmail so you can send it off from hotmail if you want.