Apple tree grafting - planned success rate and other questions
I've decided to try grafting some wood from some friends' favorite apple and pear trees onto rootstock this spring. I think I have a handle on how to collect the scions, when to do everything, and techniques for grafting, but I do have some questions that I was hoping that someone might be able to help with:
The nursery I want to order rootstock from is taking orders now for the spring. I think I will end up wanting two new apple trees and two new pear trees. How many should I buy? I should probably allow for some failure, right? Two rootstocks for every hoped-for future tree? More?
I notice in some publications, what they call "rootstocks" have a bunch of stems. I'm guessing those get separated out at nurseries, right? So if I order six root stocks, I get six stems on which to graft?
I thought I'd heel them in in our vegetable garden for the year and then transplant them next year to the field. Any reason not to heel them in in containers to allow for easy removal?
Lastly, we have large mess of an ancient apple tree in the backyard that hasn't been kept in any way for decades. I thought I'd prune it this year and for fun graft on some of the scions I get from my friends. I don't want to take off EVERY limb (and I know I'm supposed to leave a "mother limb" anyway), but it will be a fairly major pruning job. I'll seal up any cuts, but is there much risk of seriously injuring the tree by pruning it back very heavily?
Thanks in advance for any responses to any part of this! Any external resources/recommendations are welcome and appreciated.