Thanks for all the replies fellas!
Ya it'd probably get a marlin 30-30 instead of a shotgun now! It's for bear defense mainly.
12ga. is a far superior bear gun than the 30-30. If its for defense - you'll be using it within close quarters to the bear and a 1oz slug will stop bears faster than a 130grain 30 caliber. The way I look at it, if you have to aim, you shouldn't be shooting it - unless you are hunting it.
Yes, I've shot black bear with both 12ga and 30-30.
7mag was my first long rifle. I really liked it but found I liked the .270 better. 30-06 is a well proven winner and you can argue all you want as to which calibre is better - for all practical hunting applications they are all pretty equal. If you step up to moose or long range elk, then the 7mag or 30-06. You can look at ballistic chart until you are cross-eyed but unless you are a marksman or loading your own, don't worry about ballistics - these all work great. I wouldn't worry about long range hunt/shooting since you should be stalking as close as practical anyways.
Do the research on the rifle make and model, be sure to get a good reputable shooter that fits your needs. Decide what you need, don't get an older semi-automatic if you are a left handed shooter unless you are prepared to take hot brass in the nose. If you really get into it, you will by another rifle - we all did and new hunters will continue to do so. Get good optics and ring/bases.
Are you going to reload or buy factory loads? Check the pricing on shells. There are a lot of questions and many more answers. You need to speak to a few gun shops to narrow down the right rifle for you. Also helps if you go out with a buddy and get to shoot different calibres and loads.
Personally - don't get the 30-30 unless you get a hand me down rifle for free. Honestly, you're not going to like it for hunting until you become somewhat dedicated to that hunting style. A .270 or 30-06 would be most practical for you.
That's my opinion - many will agree and many will not. In the end it doesn't matter what you get as long as you hunt legally, safely and ethically.
Cheers.