the Juni is just a wee thing with not much shape or style to it really
If you like it keep it as it as use it to learn how to keep a Juni in top condition by pinching.
Any one else will tell you to stick it in the ground for a few years, but a tree this size needs abot 10 -20 to get any bulk on so use it as you can at the moment
The maple is too hard to see thru the foliage

Yep looks grafted, which ois not ideal but would it support on it own roots? Better check before Layering off. the alternative it to layer right below the roots, so the graft then gets lost in the nebari
if you wait till it loses leaves then we will be able to see the trunk and offer suggestion then on it future
Ken