It's been some time since I applied, but I hope I can offer some help...
I don't remember sending in my passport, but I did apply online for my provisional license. I could be wrong, so someone correct me if I am, but I think I printed out a form after submitting my application online, then sent in my photo with that form to the DVLA. I'd assume the passport is submitted with the photo, but I'm sure it's explained to you when you apply online.
As for not liking manual cars, just get an automatic license. I hate manuals with a passion (there were tears from me, too, when I practised!), and decided I'd rather get the license and get comfortable on UK roads before dealing with learning to drive a manual. Unless you'll be driving a manual car, there's no problem having a restriction on your license that says you can only drive automatics. It's still considered a full license. I was worried, because many jobs I was applying to required a "full license", but I was told that the restriction for autos was fine. You can always go back and get a license for manual cars later. I never got my manual license, and actually, I probably never will at this point. My husband realised that automatics are easier and really likes them now.
As for the theory test... I believe I called to book, but I'm not sure, and I was able to book it two weeks before the test. You can now book online (
http://goo.gl/A6Ucv). It's easy as long as you study. Take a lot of practice tests online for the hazard perception part of the test, because it can be tricky if you don't know exactly what to do. I got a 100% without a problem just by reading the book and spending 90% of my time learning the practice questions from the sample tests book. If you're good at memorisation, you'll have no problem studying that way. It depends on your learning style. It's much more difficult than US driving tests, so be prepared to put a lot of work into studying. Many people don't pass it the first time, but as long as you study, it should be fine. My brother in law studied a bit and didn't take hazard perception practice tests beforehand, and failed that part. Just be prepared.
As for the practical (actual) test, you book that online after you pass your theory test (you need the theory test pass certificate number to book), and it takes a long time to get a spot usually. I think I booked around 2 months in advance, but that was just so I could get lessons beforehand. I probably could have booked about a month in advance. You can pass the practical test without any issue if you get a driving instructor. I wouldn't only practice with your spouse or a friend, because an instructor will be able to give you details instructions on what the DVLA is looking for. They'll also take you through practice tests on the roads your actual test will take place on, so you'll be more than prepared on the day of the test. It can be pricey (around £20-25/hr), but it's necessary, in my opinion. You can get automatic cars, too. If you're an experienced driver in the US, it won't be a problem passing the automatic test. You'll just need to learn the rules of UK roads, get comfortable driving here and learn how the DVLA wants you to perform manoeuvres (3 point turn, etc). Having an automatic to practice on outside your lessons will definitely help. Get a reputable driving instructor that has been referred to by friends, because, obviously, some will try to get you to take as many lessons as possible, even if you don't need them. My husband's instructor did that, but my instructor didn't.
As long as you're prepared, you'll do fine. Good luck to you!