I get my Fish oil caps at Costco.  We just get the house brand from Kirkland.  Huge bottle for a fair price.  If you have Coatco near you.

The paleo way to get B vitamins is from meat.  You probably don't need a B vitamin supplement on paleo.

The main paleo way to get vitamin D is from exposure to sunlight.  If you don't get a lot of sun exposure while the sun is high, you may still want a vitamin D supplement.  I myself take 4000 IU of D-3 per day, on days that I remember.

The paleo way to prevent scurvy is from raw meat and from vitamin C in fruit.  That said, some domesticated fruit doesn't have as much vitamin C as does wild fruit, and may not have enough to balance the immune system effects of the sugar in the fruit.  Strawberries and kiwis may have adequate vitamin C, but if you eat a lot of other fruit, you may want supplementary vitamin C.  I don't think 1000 mg per day would hurt.

D2 and D3 are slightly different chemical forms of vitamin D that ultimately get converted into the active form, 25-hydroxy-vitamin-D, in the body.  Some people think they are equally good; some people think that D3 is better.  I take D3 just to be safe.  You do not need both.

The primary danger associated with raw beef comes from salmonella and e. coli contamination at the processing plant.  This contamination is only on the surface of the meat.  It can be mixed into the meat in ground beef, which is why eating rare hamburger is not recommended, and chicken comes in small enough pieces that it really has to be cooked all the way through as well, but rare steaks are fine as long as the surface is cooked.

Some forms of meat can be subject to intramuscular parasites.  This is why it's recommended to cook pork all the way through.  Fish for sushi is often frozen to a sufficiently low temperature to kill similar parasites so that it can be eaten raw - that's why sushi grade fish is different from regular fish.

The middle of a rare steak counts as raw meat, and that's where I get most of my raw meat.