I have Zipp 404 clinchers. They are nice all around wheels. For a flat triathlon or TT you could be more aero with deep dish wheels (like Zipp 808's) or a disc inb the back. But for a wheelset that is pretty aero, can be ridden in any wind conditions, and is not too heavy for a hilly course, the 404's are nice.

Tubulars are a comittment. Gluing tubulars on carbon fiber rims has to be done correctly or there is a risk of rolling the tire off the rim (a bad thing). I raced for a number of years on tubular tires, and have done most of my own bike maintenence. Personally, I have found tubulars to be too much of a hassel for the marginal benefit over modern clincher tires. It sounds like you don't have a lot of bike maintenence experenience. You might want to think twice about going with tubulars.

I would say it depend on your relationship with the shop. If this a shop that you trust to deal in quality products, and to stand behind what they sell if there are any problems, I'd really consider it. But Merlin is right gluing them is an art so either have the shop do it, or have them show you how to do it.

what shop was it? I'm in the area, Southern OC and I might know the shop folks.