It's also nice for those times when you just want your own space. Not living with another student gives you the opportunity to party all night with the co-ops but then be able to head back to your place to sleep in quiet. That said, however, it all depends on who your roommates are. Many co-ops love sharing apartments with each other, and wouldn't have it any other way. It depends on where you work.
Engineering is usually more casual.
Wear ties or skirts for the first couple days and look at what the rest of your branch is wearing. Then, just try to fit in. As for non-work, bring plenty of short sleeve shirts, shorts, and other summer gear. You will need sweatshirts and pants for the November-April period, but heavy winter jackets can be left at home. Houston gets very hot in the summer, especially towards the end of July and August.