A wetsuit will improve your position in the water and you don't need to kick your legs hardly at all to keep them in a good spot. Having said that, don't worry about a wetsuit for this weekend. If you're a decent swimmer the swim leg will be over fast. You'd probably lose more time taking the wetsuit off than you save by wearing it.
If you want to think tactics...swim hard, make sure you go easy the last 5 minutes or so on the bike, and chase a bunch of people down on the run.
On the swim consider starting on the outside (because it's your first tri). If you get off to a good start sprint up to draft off someone, but don't brush their feet with your hands or you may get a kick in the face. Also, it's a good idea to take a head-up stroke every 25 or so to make sure you're swimming towards your target. You'll be amazed at how many people can't swim a straight line without a lane line underneath them.
On the bike try to get up to speed fast. It sort of depends on the terrain. I try to really push the pace the first 1/3 of the ride because otherwise you get stuck riding in a group of people and sometimes that can lead to drafting calls. The middle 1/3+ of the bike I try to settle into a groove. The last 5 minutes or so I recommend easing off, unless there are a bunch of hills late in the ride. With your ability to run you'll have more fun and likely do better if your legs aren't trashed coming off the bike.
On the run, think about picking people off. Have the attitude that no one in front of you is a better runner than you are. Stay focused on the racers in front of you and go after them! And keep charging out there. A lot of racers will go too hard on the bike or just flat out aren't as good a runner as you are. Depending on where you come off the bike you may be able to catch people who started 5 or more minutes ahead of you coming off the bike-and you will catch tme all the way to the finish line if you keep pushing it.
Have fun, enjoy the experience!