re: care - free feed hay, grain according to vet recs, give something that will supplement vitamins (my vet had me feed general livestock pellets, I think Purina's Sunshine), use either daily wormer w/ regular worming schedule or rotational worming schedule, and I recommend barefooting, I'll get you the book recs on it but best to do a clinic or have someone local train you (a lot of times barefoot farriers will train you for four or so sessions then you can maintain on your own). Gene Ovnicek and Pete Ramey (not Strasser). Endurance riders are trending more and more towards this and are good to talk to about who in the area is the best.

And being in a run out, preferably on as much acreage as possible, is better by far than stall kept, healthwise and sanity wise for the horse. In a small herd if possible. Not kept alone, which I personally think is mean. Also only take healthcare advice from people whose horses routinely live into their 30's. Late 20's is ok but it's not that hard to get them into their third decade fat and sassy.

Awesome answer!

My computer keeps crashing so this may be multiple posts.

Books: These are mostly from five years ago or more so there may be newer versions.

Feet:
Pete Ramey: Making Natural Hoofcare Work For You
Jaime Jackson: Horse Owners Guide To Natural Hoofcare
and Gene Ovnicek - these guys do traveling clinics if no one near you does this well (and usually only, the people you want don't shoe at all).

Riding:
Sally Swift - Centered Riding (prob can get from library).

Training:
John Lyons GCM and RM with videos. See also his website training boards. Don't worry about the god stuff if it bothers you, most of them are churchy except for Buck.
Buck Brannaman videos, esp if you are using curbs.
And just for fun - Alexandra Kurland - Clicker Training for Your Horse - so much fun, I used it for silly things mostly but a very solid training method, works on all animals and most people.

More fun books/good reads:
Teresa Tsimmu Martino - Horse Nation - actual good book, nice story
Klaus Ferdinand Hempfling - Dancing With Horses - this guy is bonkers, but give it a look see if you can find it in a bookstore. Not necc practical but liked some of it.
GaWaNi Pony Boys books - again peruse if you see in a bookstore. Aside from his shaved chest, he's a nice guy, doesn't buy into bullshit ( or didn't used to before the merch fairies got him). Can't say I've found his clinics terribly useful, but speaks out for horse rescue and responsibility to the horse, which is a good thing you don't often see.

General Horse Care Books -
always found these useless. Cherry Hill has a good rep, there's "A horse around the house", the kind of huge, thick books people are always trying to get you to buy, excellent doorstop, not really worth buying.
Ask your vet for a rec on a good solid vet manual type thing and just get that if you're worried. The rest of it is better found out from people. Know basic healthcare stuff, know about colic and founder, signs and what to do, have a decent basic horse first aid kit, bandages and betadine and fly repellant wound gunk and such (try kvvet.com and similar for better prices than in tack stores), have your vet on speed dial. Feed lots of roughage, don't let 'em hang out with sharp objects, worm right, watch them closely, you'll be ok. Learn from other horse people. Lady down the street from me has a half dozen horses - and no fences. None. She's never needed them. Other lady has three horses in their mid thirties, sound and happy, all her horses live that long and are healthy to the end. There's people like that all over. Also, most valuable thing to do is just hang out with the horses while not doing anything. You'll absorb a lot more than you'd think, just watching them. Especially if they are in a herd. And play with them! You get all into training mode and forget how to play! The point of it all is to have fun, and for them to have fun too. They are full of such joy and we so rarely share that with them. God that sound sappy but it's true. They get so happy when you play with them and they realize you aren't some half crazed professorial boring machine!

And also - Fugly Horse blog. Good stuff, she holds no punches. She IS currently posting*! That's the kind of horseperson you need to find and learn from. Mandatory reading.

http://fuglyblog.com/

*(Oh so happy, she had retired from the internet for a while, so glad she's back!)

Crap, it's not her. She retired from it Nov 30th. Now it's someone new. Well, read the archives then, still educational. She does have some biases for sure and she's harsh, but she's not often wrong.