ok i renumbered your questions since you did ask 3 of them.....
1 what do you want to grow? low light set up? high light high tech?
2 the best? mineralized top soil or ada soil. the top soil is more of a diy personally dont recommend it for people just starting out. ada soil isnt cheap. eco and flourite are popular but still not too cheap. i use turface/ soil master select in most of my tanks. its cheap and has a higher carbon capacity exchange then eco and flourite.
3 depending on what kind of set up you want co2
isnt always a must.