well sunni and shia pray to the same Kabba believe in the same things (6 articles of faith and 5 pillars), the difference is on historical and some theological issues eg the Imams and the status of companions (ra).
salafis are sunnis (wahabis after abdul Wahab but its a derogatory term for them) but just like the shia which have many sub groups like zaidis and Ismailis and twelvers, The Sunnis also have sub groups like deoband, brelvi, ashari, salafi etc.
hope that helps - my advice it stick to the basics rather then any sectarian group.