I know there can be a problem with coolant leakage past the lower end of the studs and into the oil but I think you should not try to prevent it by forcing the stud into the crankcase. Thread sealant is required. You stand a chance of damaging either the threads in the crankcase, on the stud, or both and risk splitting the casting if you crank it in to refusal
Locktite blue would do or anaerobic setting pipe dope.
Indeed -- IIRC, the general guideline for studs is to install not much more than hand tight. You want the load spread out along
all the threads, and if you screw the stud in too tight then the load is concentrated one end or other of the threads. And yes, you'll want some sort of sealant. I generally install studs with blue Loctite....