The person that told you to use kerosene - dont ever believe anything they ever say again haha!
As above, a clay bar will remove tar. If its really covered then you get dedicated tar and glue removers which may be worthwhile, but if you're getting a clay bar kit anyway try with that first
If youre doing it by hand you have to be realistic about the results - itll never be absolutely swirl free, you just cant get the same finish as with a machine
Personally id suggest paying once to have the car detailed, as it would save you buying the materials, then keep on top of it afterwards with a decent wax - might work out cheaper for you