Sand from the beach?

I want to set up a marine tank (I think its about 35 gallon) with 4 or 5
fish and some live rock *maybe* coral. Can I use sand from the beach? This
is of coarse a salt water beach. If I can is rinsing enough or is there a
better way to clean it?

Also the tank I got is used and I need to clean that, is water enough? I
have heard of some people using vinegar too.

I am not new to aquaria but I am new to salt water so thank you for any
advice you might have.

Kelly