You can get a Sora/Tiagra bike of last year's model for $700, probably. In my opinion, this groupset is decent because it gives you nine speeds instead of eight (2300 groupset). I've also ridden Sora/Tiagra. It works well if it's tuned and set up correctly. If you can, you may want to get Tiagra shifters because Sora comes with thumb shifters instead of paddle shifters. Worth the extra cost in my opinion.

If you're are in between sizes, I'd go with the smaller one. The only real drawback of running a longer seatpost and stem is that you may have a bit of saddle to bar drop. It really depends on how each size fits though. If the bigger one fits better than smaller one, go with the bigger size. If you're indifferent, go with the smaller one. That way if you become more flexible you can begin lowering the stem, which could be limited with a larger frame.