Additional Pictures:

Your tree looks great. You should expect significant leaf drop caused by transplant shock and a change in light conditions. Don't stress... it will replace those leaves with new leaves better suited to the new light conditions. Do not fertilize until you see the start of new growth; then fertilize with a good citrus fertilizer applied at the drip line and watered in well. Pruning: we prune out anything crossing the center; anything growing in a downward direction; and anything touching the ground. Don't worry about pruning off a few fruits; in time you will have more than you can use.

I would give it a good Imidacloprid soil drench, if you have not already; and at the same time a drench of systemic fungicide. If you repeat those applications 2-3 times per year, that should be almost all of the preventative chems you need.

Listen to John. He is the real Meyer lemon guru!

Great tree! Good luck with it. I agree with Vladimir...listen to John and George!

That's a beautiful tree! So many lemons! I also wouldn't trim the tree yet, as long as the lemons are not touching the ground. They tend to have more of a bushy growth habit, and since you just transplanted it you don't want to mess with it anymore.

I just can't get over how beautiful and big that tree is! What a great purchase!

Thank you all so much for the feedback!!

So today I will go to the store to get the Imidacloprid soil drench and the fungicide (had no idea I needed these). Also neem oil for the leaves which seems to be mentioned a lot to keep pests away. Is it okay to apply all three of these on the same day?

I will fertilize once we see some new growth. This was the fertilizer sold to us (supposed to be specifically formulated for South Florida?): http://www.flnurserymart.com/products/fertilizers/fertilizer-citrus-and-fruit-trees/

I checked again this morning and the tree definitely has a bunch of very small spiders on it. I thought this was just from the environment (we have tons of spiders down here) but read it may be spider mites? Maybe I am just over complicating things, but it seems that a lot of the leaves are getting these black bumps all over the back side and you can almost see through the leaves when the sun is hitting it. Hopefully those three treatments will clear up whatever this is, if it is not normal after transplanting. Again thanks for the feedback!!!

At the same time you do the soil drench, I would spray the whole tree with the same two chemicals (they should be tank mixable, so only one application): both the imidacloprid and the fungicide are topically active (kills what is there now) and systemically active (prevents future problems). I wouldn't spray neem oil now; it is probably too hot and it will burn your leaves. Horticultural oils are best for control of scale. Spider mites are a problem; they are very tiny and leave little web-like signs; they are easiest controlled by washing your tree with the hose (something you should do about once a week). Ordinary garden spiders are good; because they attract wasps which are always beneficial; and because their webs catch a lot of other insects. Besides controlling a number of diseases including scale, wasps sting the spiders to paralyze them; then they put one in with each of their eggs, so when the baby wasp hatches it has something to eat.

Thanks again for your help! Appreciate it!

Final question (hopefully), are these two products okay as far as fungicide and imidacloprid?

Fungicide: http://www.homedepot.com/p/Southern-Ag-1-Pt-Liquid-Copper-Fungicide-100048940/100599149

Imidacloprid: https://www.lowes.com/pd/BAYER-ADVANCED-Fruit-Citrus-Vegetable-32-fl-oz-Garden-Insect-Killer/3170999 

The Bayer Advanced is as good as you can get for home use. The fungicide is good; but appears to be topical only and not systemic. Bayer has a product called Silvacur, if you can find it or just ask your local nurseryman for a good systemic fungicide. In S. Florida with its high humidity fungus control is very important.

Wonderful! Thank you for your help!!