How long should it take for a good farrier to back up long and under run heels, and long flared toes?
Depends on many factors IME, but will generally take at least a few trims, very often substantially more.
Landing hard, toe first. I am guessing this isn't good considering it's making my mare very sore. What are the causes, and what kind of damage is happening?
Shock & concussion to the tip of P3 - and corium, laminae, etc. Shock & concussion all up the legs, because it isn't dispersed. Concussion & damage to the extensor process of P3 and the coffin joint, leading to low articular ringbone. Strain & torque on the navicular region & lower DDFT, causing 'navicular syndrome' & eventually associated bony changes.
Hoof shape, do horses hooves have to grow in a uniform and even shape to work the best?
Yes, generally. But it's not good to cut a 'uniform' shape hoof on a skewed limb or such.
Spice's legs turn out and every time he takes off part of the flare on her back hoofs she gets sore until it regrows. It isn't pretty but it seems to be working for her, and at 14 should I expect that to change?
Only speculating of course, but if your farrier is making your horse sore each trim trying to 'correct' something, I think he is possibly doing the wrong thing. I would guess that perhaps rather than just dressing the flare & ensuring good hoof balance(for that particular hoof/horse), he is changing the balance - shortening the hoof on one side from underneath or such - and while there have been studies that show bone remodelling can happen at any age, there are so many other factors- such as joint health, chronic pain leading to osteo arthritis, etc, that it's generally accepted that 'conformational faults' shouldn't be attempted to be changed past about a year max(depends on which bits), let alone 14yo.
Hole in the frog, a chunk of Spices frog is gone, I keep it clean and it is no longer sore to touch. Not sure what caused it. How long would it take to regrow?
Could be thrush, could have been an abscess that's blown. Shouldn't take too long to resolve & regrow. Disinfecting the frog to kill thrush(but it's important not to over do that either) and keeping the horse in a dry environment is helpful. How long it takes will also depend on state of hooves & how well they function.
Is there anything as a owner I could do to help her long toed, under run heels, holey frog hooves?
Frequent & correct trimming, often enough to prevent overgrowth. Feeding a healthy diet & well balanced nutrition. No shoes, at least until the long toes & heels have been corrected. Good dry, firm environment, treat thrush. Provide hoof protection wherever necessary, in the form of boots or such, pref with frog support pads if the frogs are receded/weak, to allow the horse to comfortably start landing heel first.
Where is a good source of information on hooves? Seems like there is so much out there but what is true, and relavent is tricky to find.
Hmm, & it depends who you ask too. The thread link in my signature below is a start.
How do you talk to a farrier when you're not even sure what you're talking about? I don't know what the goal to have Spice's hooves look like so I'm not sure if we're making progress too it.
Progress should be relatively clear - the horse should be looking & moving better after each trim than before. As to discussing this with the farrier if you're uneducated about it, that can be tricky - I can only suggest you get yourself educated about hoof health & function ASAP. Asking the guy lots of questions about what & why he does things will help you understand his ideas better(you've asked some pertinent questions here
), but may not give you an idea whether he's good, bad or indifferent.