This past June, I planted a Flowering Pear tree in my back yard. Any tips on getting it ready for the late fall and upcoming winter? Winters here (South Eastern Pennsylvania), tend to get pretty cold, and I'd hate for my newest addition not survive due to improper care.

The best thing you can do for a young fruit tree is to use tree wrap on it so animals will not eat the tender bark during the cold months when other food is scarce. Be careful with mulching fruit trees this can back fire and attract mice or moles that will nest in the mulch,eating the bark and roots.
I have left mine unmulched and did not tree wrap it either as mice have not been a problem in my area. I have dogs. I live in a very cold winter climate and am happy to say my pear tree has had a very productive summer. It was the third growing season since we planted it. I have pear pies in my freezer to prove it. I grow organic too.
I am a retired landscape designer.

Water well during the dry autumn months and plenty of mulch over the root ball. You do not need to knit a sweater.

Water it, mulch it. I just panted a bunch of trees to. I have tons of plants and trees. Keeping it wet and mulching will be all you really need to do. You can make some egg shell water and use it to water it ever so often.
Dry egg shells and then break it up real good, add to water let water sit over night. Use next day this will help any plant grow better. Been using this since I was a little girl My mother told me this and it really works. Thought I had lost a few plants in my days and use it and they came back. I am 45 now. I have a jungle here. More plants than I need ... Want some? Tons of trees too... LOL
Good Luck. I am sure all will be fine and if you got animals trying to get to it in the winter which I don't. You can put some chicken wire around it. NO biggie.

the plant is equipped with all the tools to handle winter.

plants have for thousands of years