I'm not the one to decide, but yeah I think you should be fine. Best to do the local series races first though to make sure you're safe on the start line. it can be different than one might think.
I would guess that buying a used board would be cheaper than building your own though. especially since you'll usually get a fin set with it.
Who decides about the gear?, i have experience racing windsurfers and hobies. still dont have a clue what the flags mean. just read the wind and get to the mark. Avoid the crowd. they are probably as lost as i am? But seriously who do i contact about gear ?
the start is very similar to sailing & windsurfing, but also very different because of the kites hanging out 25m away. The basic flags are easy. Basically flagging for: "5min, 4min, 1min, go." It's not particularly difficult, but a race where world champions and other top riders travel to compete is not the best place to learn from scratch. that's all. But most people out there pick up on the rules very quickly, so few people are 'lost.'
If you are making your own board, for reference the Mikeslab and Aguera boards are probably the best proven shapes out there right now. The North, RRD, NJS, and Royal boards all show potential but are still new shapes.
Anyone can get any board, but it may take some time.