Dwarf stock fruit trees are absolutely fine in the ground. The stock they are grown/grafted onto means that they remain small in the root ball growth and the only consideration you need to give to this when planting in the ground is to make sure the soil it goes into is good soil. They should be about 8 foot apart if they are the dwarf varieties - these are the ones often used to create stepover edging to borders and are planted that far apart like you might see in Victorian walled gardens.
I’ve seen this before as an example of spacing with apple trees - http://www.orangepippintrees.co.uk/articles/fruit-tree-spacing-guide
Generally dwarf rooted apple trees don’t need pruning every year like other apple trees, but some pruning can be done to shape it or to thin out some of the branches, and allowing circulation of air. As you say these have grown and grown, maybe some pruning will help - to be honest it would be easier to google pruning or check a fruit book in the library as trying to explain it in a post is not easy. But yes you can prune them to get the shape back - I would try not to prune too much in one go as the tree will respond by trying to grow more branches rather than putting it’s energy into the next fruit crop. Prune say a third of the branches you want to when you plant them out and then a third in the winter and the rest next Summer.
They will be fine in the space you say you have, just remember some decent soil for them and a stake. We have a small garden and have an already established smallish apple tree (60+yrs from when the house was built) and have 3 additional apple trees (one a 3-in-1), a pear tree (3-in-1) and an almond and they are all thriving.