I haven't planted apple or pear before, but I can give you a few general tips about planting fruit trees in general.
If your soil is clay-y and has a tendency to get soggy, then plant the trees a little higher than level with the ground. Just about an inch or so.
Don't dig a circular hole. Your soil is likely a bit denser than the soil the tree is potted in. Roots generally take the path of least resistance and if there's a circular wall of dirt that has more resistance than the roots would face if they went sideways, they may end up root-binding themselves.
When amending soil for tree planting, there's a lot of conflicting advice. Something that is becoming more popular recently (and which makes sense to me) is focusing the majority of amending efforts in a donut shape around the tree trunk on top of, or in the top few inches of, the existing soil. This is in line with no-dig thinking, and it mimics how nutrients enter soil in nature and serves to leave any soil organisms (fungi, bacteria, etc) and soil structure undisturbed. So I would suggest that you maybe chuck a bit of blood and bone in the hole, and then put a ring of compost around your tree an inch or more thick, and then definitely, absolutely mulch. But make sure the compost and mulch don't touch the trunk above the soil level. This is particularly important when it's wet as it can lead to ringbarking. Some people put guards around the trunk to keep the mulch from touching it.
Definitely mulch. Mulch is the best for trees. Arborists mulch would be my top pick for this because the woodchips are great for inviting and hosting fungi (which is great for trees) and the twiggy bits and mulched leaves have higher concentrations of different nutrients (such as potassium) to the chipped trunk/branches. So, as the mulch breaks down over time, it'll feed the soil with a wide range of good things.
When spacing, consider how big you're going to let the trees get.
Research pruning. My favourite resource for this is Kath Irvine's book, but that likely isn't available wherever you are. There's a lot of resources out there though.