What breed to you mean by ID?
By "novice" you mean you consider yourself a beginner and not an intermediate rider, correct? (I'll just be assuming you mean beginner, no offense)!
Since you said you're a beginner, I think you should concentrate more on the experience of the horse then breed. Personally, though, I'm fond of TBs, they can be a little "hotter" than you may be used to, though, especially if you get a full TB as opposed to a cross.
I've also been reading about buying and ownership. I've read that for a vet check, you're generally looking at $500. I may be wrong though, and it probably depends on location and the individual vet, and what you get checked out.
How much to get checked out? Well, if I was buying, I think I would want whatever is usually done, plus get the legs x-rayed.
As for riding experience, I always think that the more, the better. In a perfect world, several years of consistent riding (weekly or bi-weekly lessons), several months of leasing, maybe a quality horse camp here or there. However, with what you've provided, I really can't give you a good opinion on whether or not you're ready. Perhaps ask your instructor what she/he thinks.
Handling experience, again, the more the better. I like as much or more handling experience compared to riding.
Some people recommend waiting a day or two before riding the horse, however others ride the horse the day they're brought to the barn. I think it all comes down to personal preference and how the horse seems to be at the time.
So you want to show in hunter, possibly jumping as well when the time comes, and also trail ride with the horse?
I'm 5'4" and 170ish pounds, I jump :). You are more than fine!
I think you should be looking for a jumper with experience, but enough drive and talent to get you through at least the beginning of your show career. Preferably a horse with experience in the show ring, having it in the hunter ring would be preferable. Something not very spooky and sane enough to take on trails.