Wear what you want to, miz, rather than what Sqad wants to see you in.
Also, relax, and stop panicking about his motives. Until you aren't actually a couple he has no reason not to keep his eyes on the website, and you have no reason not to either. So far you've found a guy who has asked you out for several dates. He's more than just interested in you (if you were meant as a "bit on the side", by now I'm sure Mr. Player would have lost interest...), so if you are in him, let it play out and try to relax about it all.
How you dress, if you're worried about that, ought to depend on what you feel comfortable in. If you still aren't sure what you want, then dress accordingly, and if you are, then dress for that, too. Either way, I think he likes you, so the next bit is to decide whether or not you like him back. You'll find making that decision rather a lot easier if you're just a bit less paranoid.