Of the things you have mentioned I would get a reasonable pair of shorts first, whether they are bibs or not is a personal preference. However, most people seem to end up with bibs and don't look back.

You will probably be okay in a wicking tee, but a good cycling jersey will wick well, can be unzipped, has pockets for the endless amount of crap that people carry, doesn't flap about in the wind (assuming it fits well), and let's face it, looks better.

Clipless pedals are something that you will likely want to upgrade to at some point, for now I would just get used to riding the bike. Oh, and when you do upgrade, I'd like to pre-congratulate you for falling over at that stop sign with both of your feet clipped in...