Hi Christine,

We are happy to help but, need a clear picture of each problem. Also, a little history such as, how old the trees are, what you have sprayed on them this season and when each spray was applied.

If pictures are not possible, then we can provide you with information about care, pests and diseases that you can compare with what you have.

I will watch for your additional information.

I am not sure what is affecting the quince.  It is perhaps earlier cold damage when the leaves were young and tender.  I would need closeup photos of individual leaves top and bottom to make a better diagnosis.

The apricots have peach leaf curl, a fungal disease.  This is somewhat rare on apricots, some research indicates that the strain on apricots is different than the peach strain. If you have time I would appreciate a few more pictures showing the various types of leaf symptoms.  This is controlled with a late fall copper spray (after 50% of the leaves have dropped). Ziram and chlorothalonil are effective as well but may be harder for you to find. 

Pears have pear blister mite.   This is handled with dormant oil applications.

https://www.virginiafruit.ento.vt.edu/pearblister.html

You could consider if your oil coverage was sufficient--the right kind of oil, amount, and enough water to get good coverage.  If you have nearby woody hosts with an infestation of pear blister mite, control will be more difficult.

In the last group of pictures, all the pictures showing the peach leaf curl are from peach trees.  I looked back at your first set of leaves, and this one was also a peach....I was swayed by your photo label.  Apricot leaves are much more round.

The symptoms on the quince don't look like insect or disease.  Maybe stress from the freezes.  

It will be easier to spray a shorter pear tree, which should help with your disease issue. 

The normal pruning time for fruit trees is late March to mid April before there is much green development.  Some pruning can be done later than this but it is best to get it done in the next few weeks, but less aggressive, i.e., don't take away more than approximately 10% of the canopy.   

https://www.canr.msu.edu/resources/smart-gardening-pruning-and-training-backyard-apple-and-pear-trees

In bringing down the height of the tree, the important point is that you should prune slightly above a somewhat dominant side limb, a so-called boss limb.  This boss limb will help to suppress a strong regrowth response at the site of the cut.  

You can see this illustrated at the following web site.  

https://www.wintergreenhouse.com/plant-guides/fruit-trees/https://www.wintergreenhouse.com/plant-guides/fruit-trees/