I have a 09 FX7.3 and I have put a light a Edge 705 on it. I use it to measure distance travel, speed, average speed, time, % of grade, elevation, and total elevation gain. If you want a computer, I would say it is not worth it to buy one with a heart rate monitor or maybe even a cadence meter. Right now, those numbers won't mean anything to you and you won't be a consistently performing cyclist.
Also, water bottle cages and water bottles are musts.