There really is no difference in reloading between the .308 and .30-30. They both have to be prepped the same, and the same techniques apply to loading each. I guess the one difference would be that if you are loading the .30-30 for a tubular magazine, then you would have to load flat nosed bullets only. The .308 can be loaded with spitzer type bullets.

As for your second question - I would say it is the other way around. The .30-30 lacks the case capacity to push bullets of the same weight to the velocites of the .308. Now, you can load the .308 slightly milder with the right powder and loading techniques, but I don't see a reason to do so. Either way, I don't think a deer will know the difference between being hit with a .30-30 or a .308.