re 2nd tree: A straight section is only straight in relation to the ultimate size of the tree. With this one the way it is I see a larger tree. you have not given us a scale so hard to judge how big it is but roughly 1/3 of height is a reasonable height for 1st branch. If your existing 1st branch is higher than that think would it be possible to go outside good guidelines or can you cut to make it lower? Also look at a slight change of front - try rotating slightly clockwise to make the trunk go away and left rather than straight left??? I see 1st branch left, back branch where that ugly cut is, maybe a right branch between?? The upright branch/trunk on the right could be removed completely or might make a low right branch?
I think Isitangus' idea of cutting at the sacrifice branch would leave the trunk too straight and upright when it thickens a bit more.
Leader at the back will no make any difference at this stage. If you tidy that stub now it will be healed in a year or 2 well before this tree is ready to pot up or show off

There will be more cuts to heal before then too.
If you want to grow a smaller tree then by all means cut lower - tridents will bud pretty well and who knows what will grow for you but this option is always hit and miss.