4064 is a good powder for the 308.
I prefer Varget, others prefer RL 15.
So your powder choice is fine.
Looking at Hodgden's site they show a minimum of 43.0 Grains of IMR 4064 and a maximum of 47.7 grains for the 150 grain bullet in a .308.
Double check your manual for the 40.0 grain load. Double check and zero your scale to make certain your powder charge is correct. With 40 grains of 4064 the load should not compress the powder.
It is OK for the bullet to contact the powder. I like my loads to be at around 100% case capacity. Make certain you follow your load manual and again double check your scale. 40 Grains does appear to be on the light side.
As far as bullets most will work fine. I prefer North Fork, Swift, or Barnes TSX.