Got invited to a wedding

[frosty]

and I have some questions. The person getting married is someone I used to work with (and at one point had a crush on) and we became friends that way, but never really close friends, just "work friends." I've not responded to the invitation yet because I'm not sure if I should go. I say should as opposed to want because I would like to go yet I'm not sure if I'm prepared to go. And perhaps here you guys can help me understand what to expect at such occasions. First, what are approproate gifts? Second, must I go with a significant other, as I expect many to do? I'm single and I'm afraid that it'll be a bit awkward for me to come alone even though the invite is for me. Third, what to wear? Are weddings usually a black tie and tux event?

Obviously, as you can see, I've never really been to a wedding, well maybe one or two in the past but I can't recall how it was like, and I probably wasn't that self-conscious then.

On a side note, I didn't go to the baby shower mentioned in a past thread, but I gave a card (that I made) with a Target gift certificate ($50, which I hope wasn't too much or to cheap).