My husband and I did it this way. My replies as follows.
Does he need to bring anything with him when he travels over for the wedding? I am told that he should not offer up information that he is here to be married. If he is questioned and it should happen to come up, are there any documents he could/should have prepared to show them?
Return plane ticket would be the best thing for him to have.
Does anyone forsee any issues when we go to get the marriage license and/or has anyone filed for a marriage license by proxy?
We had no problems. In fact, we went down to the town hall the day after my husband arrived and applied for our license. To be sure though, check the laws in your state. I lived in IL at the time.
Once we are married, I will apply for a spousal visa. Does he have to be present? Is fast track the best option?
I don't think it's a requirement that he be present, but I believe you do have to have his passport. (check the instructions to be sure). I don't have any experience with the fast track process, but know that the people here who do have stated it was so easy and made the whole thing go a bit faster once as the consular's office.
And finally -- with six months to go until we wed, is there any part of the process that I can or should get started on?
The only thing I would recommend is gathering your documents. They ask for a lot and it's good to be prepared with a bit of everything. It also won't hurt to research jobs over here as one of the requirements they look for in your application is whether you'll be looking for work or not. I had made some e-mail enquiries with a few people and the agency I worked for in the US had a branch in London so I got in touch with them as well. I had copies of all my e-mail communications with folks along with my CV.
How much will the scrutinize the amount of money I have when I move and how much to you think is enough?
We had pretty much nothing when I applied for a spousal and I got it with no problems. I had nothing in savings and neither did my husband. In fact, the bank statement I provided went into an overdrawn balance and I thought for sure they might make issue of it. We had no problems.
I think what they're mostly looking for is whether or not your soon-to-be-husband will be able to support you while you look for a job or if you intend to stay at home. I also think that the issue of savings only really comes into play more if you're applying for a fiancee visa because then you're looking at being in the UK for 6 months without being able to work. So it becomes a bit more important. Whereas on a spousal, you can work right away.
If your fiance has a steady job and steady housing then I don't think you'll have a problem. Having savings doesn't hurt, but hopefully our experience of having nothing and being successful will ease your mind a bit.
Best of luck!