Well that's the good, but here's the not-so-good. Only two things, really: One, why is everyone in such a damn hurry? Playing an heroic mission with some other guys and we get to a conversation. Suddenly the group chat is full of...
Press spacebar to skip conversation
Press spacebar plz
Keep in mind that, at this point, many have already either leveled a few toons, or have done that particular heroic a number of times. There are also those with the "wow" mentality derived from cross server LFG tools that tend to allow one's focus to be central to only their needs and desires.
I too tend to push the space bar at times after leveling a number of characters. I space bar automatically on previous content, but at least have the courtesy to allow other to read it. Some are not so courteous.
I would just explain that it is your first time through and to bear with you. Any reasonable player would tend to do so. If they complain, or purvey any vitriol, I would either note or remember the name for future reference. If they become vile, I would report the conversation (there is a tool for this) and put them on ignore.
In regard to leveling, being slightly higher in level makes leveling a bit easier and quicker. You can pass on side quests and just focus on both your class quest and planet quest if you choose to "catch up" and move to the next planet. They are all categorized in your quest log and skipping side quests do not penalize or prevent you from proceeding. Planet quest do not either, but they are chain quests with a beginning and end.