I've spoken with several couples in Tokyo that were told by the US Embassy here that they should get married before trying to move to the US, since marrying afterwards would be a nightmare.

My understanding also is that its way way way way better to get married overseas and then try to get into the US. Sorry, I don't have any links for you.

It will still probably take a few months to a year. Which is probably going to make it difficult to have a job lined up in advance.

In any case its better because it doesn't require you and your spouse to be separated.

Does "fiancee" even have any legal defintion in the US? Nobody signs anything when they propose and I'm pretty sure that states don't recognise it as a legal status, at least not until various common-law cohabitation conditions comes into play.

I admit that this is personal experience. However, a quick google of "fiancee visa vs spousal visa" seems to back me up.