1) we often ask manufacturer to panelize our PCB (panel means, they will "clone" your small PCB and place them more times on a bigger PCB)
2, 3) Usually FR-4 (but depends on stackup and impedance requirements)
4) We usually use Gold (the pads on your PCB will be gold)
5) Tented VIAs (covered with mask, with the Green / Blue / Red etc. color)
6) 1 oz or smaller (depends on application, stackup and impedance requirements)
For assembly, send them pick and place file.
The easiest way for you could be, go and download one of our projects. Go to PCB, have a look at "Manufacturing notes layer" and have a look inside Released file directory - you will see what everything we provide to PCB manufacturing company and assembly house to manufacture our boards. Try 28 Pins or iMX6 Rex projects:
1)
http://www.28pins.com/my-account2)
http://www.imx6rex.com/my-account/