Thank you guys

So I've been recently a subscriber now for three weeks, and I saw this this player on YouTube who started doing the the beginning of chapter 1 at level 50. Here is my question. Is it possible after the ending of any class prologue story, will they be able to do SIDE quests on any planet in sequential order (depending on class) first then do the main storyline for last? Also do flashpoints, warzones and space missions go along with this too? I appreciate any help I can get. I'll give a example. I have a level 16 Sith Marauder right now who will go to Balmorra, and I do NOT start the chapter 1 storyline quests from there. Instead I try to gain levels by doing side quests, warzones, flashpoints, ect. I know Balmorra has a level range from 16-20. Like say I get those 4 levels from side missions, pvp and flashpoints only. Will I be able to do side missions in Nar Shaddaa and will they actually appear from 20-24 if i did NOT do any storyline quests at Balmorra? I'm not good at explaining things but I'll take any help I can for a answer to my question. Thanks in advance