Manifold gaskets go on dry. You could use gasket adhesive but it's not really going to help them seal.
I bleed the coolant with the car parked going up a hill. Turn the heater on full hot, fill the radiator with coolant (and distilled water if it's not pre-mixed), open the little plastic bleed screw (carefully) next to the radiator cap, turn on the engine and wait for the bubbles to stop coming from the bleeder. Close the bleeder, fill to final capacity (Kalt? line) and take it out for a short drive. If you get good heat from the heater (and you don't see any obvious leaks) you should be good to go.
Snug is good for the manifold. They're only 10mm nuts, right? I'd go hand tight then 1/8 turn or so. I use my little 1/4" or 3/8" ratchet for small stuff like that. Don't go putting them on with a 1/2" impact wrench.