I was in the same boat you are 3 weeks ago. I am still learning the draft way of things and learning about her. After getting my current belgian I WILL NEVER GO back to the little guys.
If you can get that book from luvmyperch DO IT! I bought one from amazon
and it has been a great book to reference to.
I currently feed my girl half scoop purina strategy in 1 cup oil with some coastal or sometimes she gets a SMALL handfull of alfalfa or alfalfa pellets. Rest of her diet is on the pasture. As I work her more I will increase her feed.
It is always wise to worm a new(to you) horse. I got mine and after bathing her I found a lot of bot eggs as well as she was skinny on the pelvis. I have given her bot treatment, and will actually begin power dosing her tonight. Worming a draft you buy 2 yes TWO boxes of power dose. 1 box = 74.99 here.
Expect farrier cost to largly increase! Mine did. Also make sure she will not just give her feet but will let you hold them for a long period of time and or mess with them. When they so much as twitch their leg it will send the farrier flying about 4 feet (happened 2 weeks ago) and yes the farrier was TICKED off. I now have to have the vet come out and knock her out to get trimmed as well as spending over an hour a day messing with her feet so she wont do that again. Mine didnt do it out of agression she just wanted to move/shift her weight. Some farriers have shoeing stocks, cost more to get done but if tyou can find one with stocks DO IT!
Im still learning myself...