Prune this tree: Red Plum
Let me start by saying this is my first time ever pruning a tree, so I'd like some help. My idea is that eventually I will plant 6-8 fruit trees (including a pollinator for this plum, of course) in raised beds above hard clay on a strong slope in my backyard. Until I'm ready to do that (hopefully sometime this spring) I plan on leaving this in the nursery pot (or root pruning and repotting if that would help growth at this stage). I bought this on sale for $6 a couple of days ago. It's labeled a "Red Lee Plum," although I can't find any reference to that cultivar online.
This tree has a caliper of approx. 1/2inch, its main growth reaches about 40" above the soil and the very highest of the outgrowth reaches 6'. It's just starting to bloom now.
Ultimately I would like to keep the fruit trees that I plant on the slope in the 6-8' range for ease of access. I plan for this to be a "mini-orchard" as a selling point when I put the house on the market in a few years.
1) How old is this tree?
2) Should I leave it in the pot (or a larger one) for now, or would it be better to go in the ground ASAP?
3) Considering the above, should I prune it now, or later?
4) I've seen a lot of videos of planting trees like this and then topping them back to knee high to balance out top vs. root growth. How long does it take to recover from that? Should I do that? The trees in those videos seem somewhat smaller or younger than this one. What does a fruit tree that receives that treatment look like after say, one growing season?
Thanks for any and all advice!