Can this be installed flush in the ceiling?

My crew couldn't do it. It's about 5 inches off the ceiling. You also need to order 2, 6" brushed nickle nipples to feed it water. Works Great! Took my first shower yesterday!

Do the jets & overhead work at the same time. Are batteries needed for led & if so, how do you get to them?

This system comes with regular Mixer Valve / 3 Way Diverter (one function at one time). If you need an Advanced Thermostatic Mixer Valve which gives you flexibility of using one function or two functions at the same time please refer to the below listing: https://cascadashowers.com/products/20-square-ceiling-mounted-thermostatic-shower-system-4-rainfall-mode?_pos=8&_sid=7dae404e4&_ss=r  ,we have it with led lights in stock,  or call us at 800-766-7428. No need for Batteries, LED lights work on Water flow and temperature.

Does the whole house have to run in 3/4 lines for it to work properly?

No. no need to have 3/4" lines for the whole house. This valves is designed to work with 1/2" or 3/4". For this particular system (20" Square Shower Head) or smaller size, a 1/2" supply line is sufficient. for Shower head 24", 31" & 40" size a 3/4" supply line is required. The most important factor for this system (regardless of shower head size) to work efficiently, is to have a minimum water pressure of 40 psi.

Do you haves this product in brushed finish

This product comes with Brushed Nickel or Oil Rubbed Bronze, but it is special order and require 2-3 weeks manufacturing.

I installed the system and love it but can't figure out how to install the hand held shower holder

It comes with two Wall Anchors (A) (for Hollow wall options), two Screws (B), and two Wall Bracket (C), and Allen key.
1. Install Screws (B) through Wall Bracket (C) into Wall Anchors (A)
2. Insert Holder in the two Wall Bracket, and tighten it with Allen key (provided).
If you need additional information, please call us at 800-766-7428.

Brass outlet in this set - contains LEAD? My plumbing inspector is requesting more info.

The Brass outlet doesn't contain lead.

What powers the leds and where can i control them from

The LEDS are only around the perimeter hydrostatically and thermostatically controled. Cold is blue, tepid green, hot red. Am satisfied with this product so far and don't regret spending the money.

I can't get the water to mix 1st left turn CCW on top valve is for the hand held shower then second below i turn and can only get full hot or cold?

1. Unscrew the cartridge clamp nut (take note of the orientation of the cartridge) and pull the cartridge. Wash the cartridge, and make sure that any trapped debris has been removed.
2. Unscrew the Check Valve (located between top & bottom knobs), and wash the filter inside with clean running water.

Who is the manufacture?

The manufacturer is Cascada Showers

What is the material of the side spray and the rainfall? Is it plastic or real stainless steel?

It is made of solid brass, and the coating is stainless steel. Hand Held is also heavy duty stainless steel, not a plastic.