Software licensing particulars

Question

I have spent a lot of time examining the various (major) software licenses and ultimately have decided upon using the MIT Licenses for my open source projects, and the Microsoft Reference License (MS-RSL) for my proprietary projects.

Not knowing much about IP law, I have three simple questions that I haven't been able to find answers to:

1. At the top of each source file that I want to protect, I need to place a copy of the appropriate license (MIT/MS-RSL), yes?
2. If so, then in this license notice, do I have to acknowledge that I am using the MIT or MS-RSL licenses? Or is it fine to just copy-n-paste the licenses in, as-is? In other words, do I need to say: SOFTWARE LICENSE NOTICE - MIT LICENSE or can I just write SOFTWARE LICENSE NOTICE?
3. Is it "okay" (legally enforceable) to just place a link to a URL (where an EULA lives) instead of pasting in the same software license over and over again, at the top of every single source file? It would be nice to just have this:

// SOFTWARE LICENSE NOTICE    
// This software and associated files is licensed. Please visit:    
//     http://www.example.com/my-license/latest    
// for full details.

That way, http://www.example.com/my-license/latest could always contain the latest license I want the source file(s) to be protected by. So if I switch from MIT to, say, APL, no code changes/rollouts are necessary. Is this legally-sound? Thanks in advance!