I notice as you go towards the end of the scaffolding branches, the nodes get closer and closer to a point where they are really close. Are these flowering buds or leaf buds?

When I make the heading cut so that a node is on the underbelly of the branch right next to the cut, does that node need to be a leaf node or does it really not matter and flower node will turn into a branch that grows out from there?

It is better to spread the branches than using pruning to outside buds- it makes a stronger branch.

On more upright vigorous shoots the nodes are more sparse and the buds more vegetative toward the base of the shoot. Toward the tip, the buds tend to be a few more flower buds.

As Hman indicated, you can identify flower buds by their rounder nature. A common combination is one flower bud flanked on either side by vegetative buds (VFV). It's also common to see just one vegetative bud on a node (V). Less common is one vegetative and one flower bud on a node (FV), or two flower buds and one vegetative (FVF), but just about any combination is possible.

I don't think a bud will turn into a vegetative bud once it's fully differentiated itself into a flower bud, but quite frankly I've never tested it (i.e. marked a bunch of flower buds and come back later to see if any turned vegetative).

I agree spreading branches is the way to go if you have the time. It allows you more options on choosing scaffolds and you'll get a little larger tree a little earlier vs. relying solely on pruning to shape your new trees.

I sense you may be concerned about pruning off too many flower buds. You needn't be worried about that on mature trees. Mature peach trees flower so profusely, you'll have plenty of flowers left over regardless of how you prune.

Sometimes, flowers can be pretty sparse if it's the trees first crop. In that case you may want to watch what you prune. I've had second year trees produce heavily for their size (as many as 60 peaches) but more often than not they only produce a few peaches (or none).

For some reason the peach trees stuck with the bent limbs better than the plum trees.

I'll continue to bend the branches down that are starting to curl up by using string and weight but I'm still going to try to do some heading cuts to get the bottom bud to grow outwards. I'm not too concerned about cutting off too many flower buds on my 1 year old trees. I was just not sure how far I had to cut back the limbs where the buds are dense at the ends because they look like flower buds. Big buds. So I'll just chop off about a foot on each limb which is where I think I see leaf nodes.