My son in law did just the same on Sunday..Giant TCR ..he said NEVER
As for your first impressions...
I sometimes notice my forearms touch the upper bar..but i tend to ride a bit more upright, so the seat is about the same length as mtb Cube stereo in the distance from seat to stem.
Tyres ,i run at around 100 F&R
As for brakes i just put the salmon pads in the front and there ok..tho after 180 discs and 4 pot calipers there some scary shyte
Buz and tingling....as said ,padding or better gel gloves and riding position.
Do a few 15 25 milers to get comfy..enjoy the new bike