Never skip any cut-scenes on your first runthrough, no matter what anyone says. There are some dungeons (Toto-Rak for one) where those scenes are tied to the associated quest, so you'll only ever get that one chance to see the dungeon in its entirety (short of creating a new character and advancing them to that same point in the story, as that's the only way to re-do the quest).

(SE really shouldn't have even allowed the "skip cutscene" option on first runs. It should only be available when repeating content you've completed before. And other players should be blocked from advancing during those mid-dungeon cutscenes, just as they are during the opening cutscene. Those failures in SE's design are why I blame them as much as I blame the obnoxious jerks who take advantage of it to ruin other people's game.)

I'm glad you at least got some of your runs with nice helpful players to group with. It's even worse for those who get stuck with the obnoxious jerks on their very first dungeon. I've seen too many threads by people whose first Sastasha run was totally ruined, and they were ready to give up on the whole game as a result, for fear there would be little else.

At least you've seen that there are helpful friendly players out there. When you get stuck with an obnoxious player instead, try telling him/her to be nicer and give you a chance (occasionally that can work, if not often), and if they still act like a jerk, try to Vote Kick them. If that doesn't work, then Leave the dungeon yourself and try it later, in hopes of getting a better group to play it with next time.

Players who are simply quiet are pretty common. I'm like that myself on a lot of runs, largely because using the chat window requires putting the controller down to reach for the keyboard instead and then taking the time to type out something useful (slow typist) while my character is just standing there. It's sometimes worth it in order to offer some advice, and if another player asks for info I'll provide it if I can, but if the other players seem to be doing well enough, my chat is often limited to a simple greeting when entering and a "thanks everyone, good job" type of comment at the very end. (Actually, if it's the tank who's new, that can make it easier to offer advice, because by starting each encounter (as hopefully they are) they set the pace of the run. When it's a new DPS player or healer I'd like to mention something to, but meanwhile the tank runs ahead and starts the next fight, it's harder to take the time out to type something.)