Hi there. I just started a Masters program at Glasgow Uni, so I know how you're feeling. I'm loving it here, so in my biased opinion you are making a great decision! 
I honestly think that you don't have to worry about getting in to any of the Universities that you have listed. You have an excellent record (much better than mine was!) and what sounds like the potential for excellent references. Also, they don't like to say it, but there is the notion that most universities are a bit more lenient on international students because they bring in the big bucks. But I don't think you would need that leniency anyway.
For the personal statement, I would look into what each application is asking. I wrote mine about why I was interested in the program I was applying for and how I thought it would benefit me and so on. But sometimes they might ask for something different. I would assume the only thing the professors can write about is what you have to offer as a student, what your strengths are, etc. Although, I've never been a professor who had to write a recommendation so someone might be able to give some insight on that.
With the student loans, as a postgrad you can receive up to $20,500 in Stafford loans. After that, you can make up the difference with a GradPLUS loan. You'll want to fill out your FAFSA first. Once you've been accepted and chosen which uni you'll be going to, you would apply for your loans. You'll definitely want to check with your uni's registry to make sure that they accept US student loans, because not all do. I used Sallie Mae for my loans, and I think a majority of other students here did as well. There's a whole process after that, but it's not worth mentioning at the moment. Cart before the horse and all that.
You'll need to show more maintenance funds for the visa application if you go to uni in London as opposed to if you went to uni somewhere else, so keep that in mind when you are applying for loans.
Good luck with everything! It's nerve-wracking and exciting, but you'll do it!
P.S. There's big cities up here too! 
I love Edinburgh; I went there as a side-trip in the Summer of 2008, when I stayed in London. I didn't get to see Glasgow, but I hear it's great. I'm just really craving London, it's always been London, my whole life...it's not logical, really, but we don't choose who or what we love nor how much we love it, do we? People call me crazy all the time, and I understand them, but that's just the way it is!

One thing I don't understand about the loans is that on several of my applications (UCL, for example) it wants to know if I've applied for loans, the name of the loans, and if they've been granted yet. I don't get this, don't you apply for loans AFTER you get accepted? I've done the FAFSA and applied for loans before, and they wanted to know what school I was in and I'm sure they checked if I was really in that school...So this is really confusing to me. Also, I saw the amount listed in US dollars, so I apply for US loans, not British? I thought it was a combination of both? Or is that just some people? I can apply for British only loans, US only loans, or both? Is that right?
I hear you are screwed on university accommodation if you don't apply early, is this completely true? I won't get my acceptance/rejection letters till early January, so I won't be able to apply for housing till mid/late January. Am I in trouble?
What I'm concerned with on my statement of purpose is "standing" out and being unique. I've read that half the time the committee doesn't even read letters/statement because of people's grades, but because I have the perfect GPA, I know they'll flip to my statement, and if I don't sound unique, I think people with lower GPA who are unique or have more extra-curricular, will beat me out! This must sound like a paradox, me not being able to create something unique as an English (Creative Writing) major, but I'm having a terrible time with it. Everything I write either seems whiny, egotistical, generic or cheesy.
The only thing I have going for me is that I basically failed out of high school and had a lot of issues in childhood (drugs, divorce, alcohol, poverty) and yet I managed to graduate with a 4.00. But, every time I write about this it sounds stupid! The only other thing I have is working/writing at a century old magazine while taking 21 credit hours. I had an amazing job for being 19 and it was a lot of responsibility that taught me a lot.
What are maintenance funds for the visa application? Are you referring to the student visa, or the Post Study Graduate Visa that requires like $3,000? I assume you are talking about showing approved loans/personal cash for getting a student visa based on the school I plan to attend, right? I have $10,000 saved now and unless something tragic happens, will have $25,000 by term...obviously that doesn't count for the Visa app, I'd barely have over that $10,000 when I apply for it.Also, I know I should be getting this info other places on the forum, but since I'm here, how long does the student visa take to get? Do you have to be accepted somewhere to apply for it?
Oh, and, do you have any personal advice/experience on pets? As pathetic as it sounds, my cat was the hardest part about making this decision. I've accepted that I'll have to leave her, but I know there's a small chance I could get a pet visa and bring her along, but part of me knows it's not a good idea and it will encumber me...the other part wants something comfortable/familiar all those miles away...and I feel bad about how depressed/lonely she gets when I leave =/.
Yes; it's definitely been nerve-wracking and exciting at the same time. I've never been more scared in my life, but at the same time I'm more excited than I've ever been; it's a ridiculous combination that creates some out of this world emotions. But, my biggest worry is now that I've accepted the move/change and decided to do it, that I'll get denied everywhere and have wasted all this hope/excitement. Just looking at the UCL calendar of events and seeing the Wine and Pizza welcome party gives me chills. If I get in I'm going to do every single thing I held back on, was afraid to do, or too lazy to do in my undergraduate career. I'm going to join every club, learn to play cricket, write for any school paper I can get my hands on...everything.