If you really want to there are recipes that use nuts as the rice portion of sushi. But I say make sashimi or roll the cooked shrimp in seaweed instead.

I have never tried this, but I imagine you could take beef stock and boil it down then add sea salt and a small amount of a fruit wine. I think that could be as close as you could get.

Sushi uses a lighter-flavored, sweeter soy sauce, unfortunately these are the ones that contain wheat also. Tamari is one of those that can be made without wheat, but they are heavier and darker, and will overpower the sushi.

If you're going to the trouble of making sushi, you could see if riced cauliflower - cauliflower chopped to pieces the size of rice grains - works.

Quinoa is not paleo.  It's basically a grain.