On bolt lug lubing. I have watched many experienced shooters use a grease filled syringe just squirt some grease on the lugs then insert the bolt. This just gums up the action and if you happen to pull a bullet on a loaded round the only way to clean up this mess is to pull the barrel.
Just a small drop of grease on your forefinger, about the size of a 17 caliber BB or slightly less, then rub the grease droplet with your thumb, You now have a this film of grease on your forefinger and thumb. Lightly smear a thin film on the bolt lug contact areas. Then, making sure the chamber is empty, holding back on the trigger, insert and close bolt. This holding the trigger back allows the unloaded lugs to carry grease to the action lugs without wiping it off.
On inserting the bolt...MAKE SURE you are in a safety area (IBS shoots require this and NBRSA shooters will like you better too) and MAKE SURE the gun is pointed in a safe direction. OR, OR, better yet, grease the bolt lugs, then insert the bolt in your bolt holster. Then at the COMMENCE FIRE command, grease the lugs as suggested above.
Well fitted and lapped lugs will gall for sure if they are not kept lubricated!!!
As to the type of grease, any automotive/machinery application grease that contains EP (Extreme Pressure) ingredients will do the job.