crabapple

Hello, we've got an old crab apple tree in our backyard. I trimmed off some dead branches but am wondering if some of the longer horizontally growing limbs should be pruned back as well (or at all??). I've attached two pics and marked where I was thinking to makes the cuts. Any suggestions are...

My raindrop crabapple was planted this April, and has done great all summer long (I'm in Oklahoma). This week, about 1/4 the leaves have started turning yellow/orange and are falling off. Is this normal? What can I do? Another thought, it has cooled off quite a bit in the last couple of weeks...

My raindrop crabapple was planted this April, and has done great all summer long (I'm in Oklahoma). This week, about 1/4 the leaves have started turning yellow/orange and are falling off. Is this normal? What can I do? Pictures attached. Thanks for the help!