First tri

No, its not needed, but a majority of the people wore one last year.   As far as the type, you should try several on to find which is best for you.

Normally the temperature of the water at this race is in the low-70's.  Wetsuits are legal up to 78 degrees, so yes, most people wear them, but at that temp it's not necessary.  The type to get is any triathlon/swimming wetsuit.  Do not use a scuba or surfing suit.  They do not allow the mobility necessary for swimming the way one designed for swimming does.  If you don't want to invest the money in buying one until you've tried it, you can rent them.  I've never rented one, but I'm sure plenty of people on this site could point you in the right direction.  One other word of advice - if you decide to use one, make sure you get some time practicing with it in open water.  They feel tight around your chest, plus the buoyancy they provide changes your body position, so they can take some time to get used to.

Don

A friend recommended DeSotoSport.com for a tri-suit. The pants have a little bit of padding, they are quick drying and good to wear...Good luck.

I would recommend a wetsuit for the Philly tri. My first tri I rented one from wetsuitrental.com; service was great and the price not too bad. After that I bought one from ProMotion. Glad I waited to buy because I'm 20 lbs. lighter and a a whole lot more fit now...