I am a quite new player in wow's huge world ad i don't know all class and their specializations. I would know which class/specialization could be near to my abitudes in others games.
Usually i like play (pve oriented) healing/support class who can buff the party and deal damage principally applying DoTs on enemies.
Can something fill my "needs"? If yes,
which class/specialization, in your opinion, can be a valid choice?
Shadow Priest (DoTs main source of damage)
Discipline Priest (Shields and absorbs main source of defense)
Holy Priest (Heal oriented)
This seems to fit your criteria of being able to provide buffs, heal and dot.
However, if you do play any of these specs you will only be doing their respective roles. Shadow priests rarely ever heal in PvE because the healers who are designed to purely heal will do it, but it doesnt mean they can't help. The same goes for Discipline and holy, they do not need to deal damage at all and focus purely on keeping the raid alive.