1. Yes, but... water with some soap or detergent would do as well.
2. Water with soap or detergent and soluble or emulsifiable oil.
3. No. Black powder residue is a mix of water soluble and insoluble solids. Nothing will remove it as well as a water based cleaner. Paraffin (kerosine in the USA) will not dissolve it or even flush it well.
You should, of course, dry and oil the gun after cleaning with water or an aqueous mixture. Many people will recommend HOT water for the self-drying action.
My regular nitro solvent is M-Pro 7. My black powder solvent is M-Pro 7 diluted 1:1 with water. I know people who use a "Moose Milk" made of Ballistol and water, everything from 1:7 Ballistol:water to 1:1.