I want to start all dlcs with the previous game in tact, but don't want to go all over the main story. Is there any possibility to start DLCs with all the side quests reset and stuff like that
Yes, there is, just download all of the DLCs (there should be 18 of them, including side quests and alternate looks for Triss, Ciri, Yennefer and Nilfgaard, plus the armor sets) I just have to remember how I did it lol, I'll get back to you later bud. I know that it jumps you immediately to level 35.