Maple Checkup (Photos Attached)

I've recently moved to Richland, WA (Eastern Washington) and have young maple tree (of some sort) in the back yard. This is probably the best tree I have been left by the previous owners. The house was built in 2005 so I can assume that the tree was planted some time since then.

My questions are:
1) When should I prune (late dormancy or mid-summer)? I plan on pruning all of my trees in the late winter, but before spring (probably early February).
2) Is this tree over crowded with limbs? It looks like it needs thinned out to me.
3) Should I spread any of the limbs out?
4) Are my proposed pruning cuts / spreader bars reasonable/needed? Please make recommendations…

Attached are photo's of the tree. The first and second photos are unedited and show the tree from two different perspectives. The third photo shows my proposed pruning cuts (in red) with spreaders in orange.

We are zone 7 (although, probably closer to a high 6). My soil is like beach sand when I dig. I have plenty of water available, but this is a desert (hot summers, cold winters with minimal precip ~7 inches a year). At the recommendation of the local nursery, I added soil amendments to try to help the tree (cutting out grass around the base) and mixing native soil with compost. I've also staked it to help with our high spring winds.

Thank you in advance for the help.