I just registered for my first triathlon. It's a sprint and is in 6 weeks.

Swim-The swim is a 250 m swim. Is it best to train doing the full distance or to do 5 x 50 full out?

Bike-I'm new to cycling and am still trying to figure out the best gear configurations. I have a Fuji Finest 1.0 and I have 3 gears in front and I think 9 in back. A good friend who is an avid cyclist told me just to leave the front gear on the smallest disk for now and only shift the back. Would I go faster on the flat on the larger disk in front? I feel like I should be faster than I am now.

Run-Will I look like a fool if I have to walk some of the run? I have a feeling I'm not going to make the whole run in the August heat after the biking and I'm afraid I will look bad if I have to walk some of it.

Clothing-What do you think is the best for shorts? I had planned to get a top too but then another friend mentioned that she had the top and it was sort of a pain because she had to pin her number on her top during the first transition so she suggested using a swim top that could double as a bra and then having a light weight jersey or top with number pinned on it to pull over your head at the first transition. What are you thoughts?

Thanks in advance for any help you can give me!