One spam flag is too little in my opinion. Someone could theoretically go around flagging people's posts and then everyone's temporarily auto-banned until an admin catches wind of it. That's a big inconvenience for everyone. It's not uncommon for a few people to have to flag something for it to go away. I actually was concerned that three flags might be too little but it seems like it's been working pretty well so far.
Re: moving the flag location...
That would require customizing the forum software which really isn't worth it in the grand scheme of things. That flag location is nested in the same location as other elements. In other words, we'd have to actually redesign/hack a lot of UI for a very minimal difference, only for it to break each time the forum dev updates his software.