I'm sorry, I did not realise you shouldnt re-pot in mid summer. I am new to this. I have tried researching the tree for my climate and am having little luck,
No need to apologize, we've all made blunders before and will again.
The tree is planted in a 16" long, 6" deep clay pot.
This is another aspect that is less than ideal. Such a large pot for such a, presumably, small tree means that the soil will have a tendency to stay wet for a longer period of time than if it were potted in a more appropriately sized container. Then again in your climate I'm sure it will dry quicker than in mine. For future reference, young plants are generally potted up incrementally, not up to such a large pot all at once.
the soil is a 50% mix of the same rocks and garden potting mix soil.
General garden center type potting soil is, in my opinion, to be avoided. This type of material, which usually contains a lot of peat, really holds a lot of water and if allowed to dry out can be difficult to re-wet. The combination of products you have chosen will allow the soil to filter between the gravel and drainage will be impeded. A better scenario is one where all components of your soil are approximately the same size. I use various inorganic materials and pine bark in varying ratios. These material are always sized with a set of screens to exclude particles that are too fine or too coarse.
Despite the conditions of the tree now, what advice can you give me that will help save my tree? should I feed it or wait several weeks?
Hold off on the fertilizer at least until you see some fresh growth.
Will it do better in full shade for the time being?
I believe I already addressed this. Dappled shade, under a larger tree, would be appropriate.
Should I continue misting the leaves or water the plant more?
The misting won't hurt but may not help a whole lot either. The hot, dry (correct me if I'm wrong) air will evaporate the moisture quickly.
Do not water excessively. The roots have been disturbed, the soil is heavy and water retentive and the pot is too large. All of these things suggest, as always, judicious watering. Your climate is different than mine so you need to make your own decisions but the soil should not be constantly wet.
The tree has never been trained or even tampered with so im not worried about the current foliage, a new set may be better to work with anyway.
Don't do anything for the balance of this year except to help ensure its recovery.
Im only asking for the best advice I can get for a tree I've never dealt with before.
In the future research a tree you are considering before you purchase it. Japanese Maples will need a period of cold weather to complete their required dormancy. Do you get temperatures below 40f? If so, for how long?