All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.
According to the view of the majority of the scholars Iblees (Satan) was not an Angel. In fact, he is the origin of Jinns. But he was with the Angels worshipping Allaah. This is why the general address concerned him too, as he had been accompanying the Angels for a long, long time. Even his state turned to be much like the state of Angels by Allaah's Will to enable him to live among the Angels. So, Satan was an "Angel" by company and way of worship but he was not of the Angels' nature; rather, he was from Jinn.
Satan did not have any followers when he was chased away from Paradise. This is why Allaah says (what means): {[Allaah] said, “Descend from it [i.e. Paradise], for it is not for you to be arrogant therein. So get out; indeed, you are of the debased.} [Quran 7:13]. Allaah also Says (what means): {[Allaah] said, “Then get out of it, for indeed, you are expelled.}[Quran 15:34]
As for how he went to Heaven, then Allaah gave him the ability to fly and move from one place to another and this is the case for all Jinns.
Finally, we urge you, dear brother, to occupy yourself in researching matters that could be of some advantages for you in this life and the Hereafter.
Allaah Knows best.