Wheels: Zip 808's or Hed 3's. pricey.
Aerobars: yes
Rear rack: yes
fender: performance hit, but mostly unavoidable unless you want to pop on and pop off
Watch all cabling and get it as smooth as possible,
more aero clothes
practicing riding in the drops.
You may want to consider getting a new bike. you are looking for a tri bike. Wheels you can transfer, others may not.
Here are the best resources on you questions:
Overview
http://www.nytro.com/Articles.asp?ID=117
Details
http://www.nytro.com/Articles.asp?ID=119
To get the most of your rides, you'll probably want to consider taking out a loan and having a sweet ride.
Regular wheels
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Guru Carbon-ti 4.8k
Cervelo P3C- 4.8k [limited availability]
Quintana Roo Tiphoon- 5.8
Guru Aero-ti-- 5.9k
Litespeed blade- 6.7k
Add Hed3 wheels, +.6k
Subtitute Zipp 808s, +1.3k
Yeah, I've done the research, but not ready to pull trigger yet. The big problem with going aero is geometry of bikes is different and you are fighting yourself if you try to ride aero on now tri bikes. Road positioning is drops is best you can get with standard geometry.