Hire an electrician. There are codes and permits involved.
Ditto! Too many variables. If not done correctly, you will have troubles with your homeowners insurance carrier. No one needs those headaches.
Here is a video regarding codes for romex
What are you running the wire for? There is no one right answer to your question.
a electric range
Electric range will need a 220 volt line and a separate dedicated breaker in the main panel. Nothing to play around with. Romex cannot be used on a 220 line. You definitely need an electrician.
can 8/3 romex be used on 220 volt
It depends on the amps and kw your stove draws. Under 50 amps and 12kw, 8/3 is appropriate. Over that and you need 6/3. Both require a 240 line with a 2 pole breaker. (In the U.S. 220 and 240 are the same thing.) Your stove is probably a 120/240 load, meaning it needs 2 hots, ground, and neutral. Distance can also come into play if the line will be more than 50 ft. from breaker to appliance. Code requires the 3 wire (actually 4 wires when including the ground), so a 4 wire plug/outlet. Check the manufacturers website for the installation instructions. Romex is a brand name like Kleenex. For most people, it refers to NM-B, non-metalic cable in the 12/2 or 14/2 size used to wire most home needs. We all just call it "Romex." Southwire is the company that makes Romex in all kinds of configurations including the 8/3 you are talking about. Stranded is fine unless the manufacturer calls for solid for some reason. If you are not comfortable wiring inside your electrical box, call an electrician.