2001 express crg van 5.7 2500

Hello
have couple of questions
1- what should be the engine temperature, I have 190 after 1 hr driving
2- if thermostat defected, is there any effect on transmission
3- how many qt should I use to replace transmission oil
Thank you in advance

Use what ever qts. it takes to get it back to full on dipstick when good and warmed up in park engine riunning.

Add about 4 qt and start checking.

Engine tempt should come up to 195 after 10-15 -20 minutes driving.