The oil is in the sump on wet sump engines. I don't think anything is actually submerged.
Assembly lube on the mains is good, cam "bearings" too. I've never used any $$$ plain bearing lube, I try and put some Redline assembly lube on them when I put the transmission etc. together but I don't lose sleep over it if I don't. If the parts are dry I dip them in oil before assembly or dribble a bit onto them.
The selector forks have to be properly in place and I usually set the transmission in neutral after shifting through the gears with the case open first to check that it all works: you have to jiggle the sprocket or clutch shaft to get the gear dogs aligned to shift if the engine isn't turning. It doesn't matter what gear it's in, you can find neutral after assembly.
Put a thin coating of 3-bond on all (very clean!) sealing surfaces and follow the instructions re wait time before assembly. Tighten the big studs in 3 steps (a turn past snug, a few ft-lbs below final, final) to final torque, following the order in the manual each time. Then torque the smaller case fasteners but be careful approaching spec torque... bolts into the case are notoriously easy to strip threads out on.
