Yeah! Pub parties have a surprisingly high rate of success - sometimes you get some duds but that's expected. There's also a LOT of French people who play, not sure what's up with that. They always use IGs so if you see "Je suis monte!" well ... dommage. Grats on the feeler!
There isn't really any etiquette when leaving a hall; I know gaf and reddit think people should thank for the hunt & when people heal you during a quest but it's not really necessary. I'll thank and then leave if it's a good group, but if they're REALLY bad then just ditch them and move to a different room - bad groups can potentially waste an hour + of your time.
PS. Here is that quest list I pasted in the chat the other day, so you know which key quests need to be done to move up an HR!
The HR numbering system stops past HR7 though - once you finish that you're considered 'G Rank', and your HR number gets unlocked (ie - you get points added each time you do any quest and that increases your HR number - that's how people have such high numbers. You're collecting points right now! You just can't see them yet.). As soon as you unlock it you'll shoot up from HR7 to like HR50.