A Few Newbie Questions

[Ihrin]

Hey guys I know these have probably been answered already but I had trouble finding them.

1. How do factions work? I only see main faction Cerulean/Crimson tracks on character profile faction page so where do you check on the other ones like Bamboo Guard and Blackram Pirate? I feel like I've seen people grinding guards as a pirate and yet when I kill them with my costume on I can't tell that I'm gaining anything or find where the dailies or reward merchants are. Additionally is it normal to not be able to switch directly between different factions costumes without putting on a neutral one first?

2. In a dungeon when I skip the cutscene am I skipping it for everyone? Is that bad etiquette or should a first timer say if they want to watch it beforehand?

3. In a dungeon what is the best way to suggest to speed up looting? Is Round Robin for blue and below items popular? If I were to offer Loot Master for class assignment of purples how would I hand out shields in a fair way? 

4. After a cross server dungeon completion is there a way to keep going with the same group; if you all go back to the dungeon lobby can you just walk back in together, can you go back to the cross server lobby together without leaving the party?

5. When to use knockdown on a dungeon boss and not get resisted? If it's already knocked down by someone else will my knockdown add to the timer?