You're on the right track.

• My personal preference is for ribeye because I think it is one of the fattiest cuts. Dry aged beef is the best - beef becomes more tender when the connective tissue has broken down a bit.
• White interspersed with the muscle is what you're looking for. If the meat is grass fed the fat will look more yellowish. You wont find grass fed beef at costco. Check whole foods.
• A more vibrant red does not necessarily mean a fresher cut. It may, but they also may just have sprayed it with something to make it redder.
• As far as cooking methods go, it really just depends on the cut. I like to pan sear steaks and finish them in the oven. Other [tougher] cuts are better with wet cooking (braising) for longer periods of time. You can try stir frying the meat in ghee (clarified butter) or coconut oil. Whatever method you choose try not to char your meat as the carbon may be a carcinogen (also, there is a difference between charring and browning, the latter of which is a result of the Maillard reaction and is responsible for a lot of flavor).

This didn't answer all your questions but I hope it helped.

Fattiest cuts: Grass fed Short ribs. Oh. my. gosh. Most fatty and delicious things I have ever had.

I'd go for grassfed oxtail- very fatty and pretty economical. I get it from www.vermontgrassfedbeef.com Save the bones- they're fantastic to make broth!

I would direct you to the following question (Meat 101 for an ex-vegetarian) to go over the different cuts of beef out there. http://paleohacks.com/questions/38647/meat-101-for-an-ex-vegetarian/38654#38654

I would strongly suggest ribeye (as has been advocated) as well as oxtails if you have access to a crock-pot (or other more ambiguously-named ceramic slow cooker).

Does a more vibrant red mean a fresher/better cut?

Nope. It probably means it was treated with carbon monooxide to keep a pleasing red color.

On a non-paleo fat/cooking style related note, I would highly recommend boneless New York Strip as the most delicious steak you can buy at the market.

To cook: high heat (10) on a cast iron skillet. Coat both sides of steak with oil, kosher salt, black pepper. Cook 2 minutes on high heat in the cast iron skillet for each side. Then pop in the oven at 450 degrees for 3-5 minutes, depending on how well done you like your steak. I like mine rare so I go 2-3 minutes. Boyfriend's is medium so 3-4 minutes is good for him.

Personally, I don't like eating fat off of steak, thus a ribeye is way too fatty for me. It's also too fatty to be cooked properly on a grill, so that sucks for diversity in cooking methods.

New York Strip is pricier, but if you see it on sale for $8.99 or so, that's a good deal. Typically goes for $10.99 though.

You've gotten some good information in previous answers on steak cuts. Steak is awesome, but it's fairly expensive compared to larger (and tougher) roasts. Roasts will have various names in the store- arm, chuck, shoulder, etc. Any roast around 3 pounds will fit in a typical slow cooker or dutch oven, and will be fall-apart delicious if braised. Google "braised roast beef" and you'll come up with a motherload of great tips and recipes. Braising a roast isn't quick, but if you can do one on a weekend day or stick it in the slow-cooker during the day while you're gone, it's minimal work and maximum eating potential.

I do this with pork roasts too (again, with various names, but usually a shoulder or butt roast), and it's perfect.

Here's a fantastic book to own:

http://www.amazon.com/All-About-Braising-Uncomplicated-Cooking/dp/0393052303

Maybe this is simplistic, but grassfed ground beef is economical and generally has a good amount of fat in it.