tassuwuf is in and of itself part of islam, but a lot of its practioners are shall we say a little on the weird side and sometimes not part of islam because of their extreme beliefs and practices.
it is better to try to understand mainstream islam first, then go into the branches otherwise you can get a little lost along the way and to be honest some of the sufis around today put people off islam or dont understand it themselves so call to something other than islam.
not a very good idea, ^ bro Dawud_uk is correct.
Sufism has regressed to something akin to polytheism, it borrows too heavily from other religions.
generally speaking, It's not worth the time, most who follow it don't want to follow all the commands and prohibitions or end up as such, they don't understand Islam well enough so seek to fill the void by other practices and ideas.
Sufism isn't a mainstream part of Islam, it opposes in its beliefs and practises the way of Allah's final Messenger and the ways of his rightly guided companions - so you should stay away from it.
If you're new with Islam, these links may be useful;