So I'm a little slow on the uptake... oops! Better late than never. Vnice - I hope this helps you out!
Here's the gist of what I was taught about a proposal.
State your hypothesis clearly.
Mention prominent sources but limit yourself to just a few, and don't quote directly. For example: As suggested by Merton, the theories of this subject have not yet been decisively explored.
Show the steps of your thesis clearly - how one proof leads to the next, leads to the next, leads to your conclusion.
If possible, use your previous sources to demonstrate how they have NOT followed your topic to its logical conclusion. One thing that universities want is originality, and a demonstrated knowledge that you understand what has been done in your area, and that you (and ONLY YOU!!) can fill the gap left in the scholarship.
Finally, demonstrate how you can walk on water and are the greatest thing since sliced bread, and ergo YOU are the ONLY candidate who could POSSIBLY do this topic. But in the humblest of terms, of course.
Yes, it's definitely a tricky thing to write. But not near as tricky as the thesis itself. Don't worry. As for word length, do a standard one of two pages (about 500 words), and fill it out for the universities requesting a longer one. But remember - if you've been able to say it all in 500 words, why force someone to read four times that length? Especially when they have about 50+ others the same length to read. If you can get your point across quickly, they'll remember that (out of sheer gratitude!), and you'll have given yourself an edge.
Okay, so there's my two cents.
For what it's worth, Vnice, the advice that director gave was pretty good. If you can make a professor forget their coffee, you've done something amazing! Good luck, and let me know if I can help any further!
Morgana