Points ar a sliding scale based on the level range of the group. In the 20's you might be getting 3 or 4 points per success. In the 50s you might be getting 15 or so per success. At 65 you might be getting in the area of 30 or so. All of that for "normal" adventures. Hard adventures yield more points but they are...well...hard. When requesting an adventure you select either normal or hard, and normal is the default.
To the question of getting points if you fail, signing up, running off to swarm kite and magically getting points later...it don't work that way.The only way to get points from a failure is this... After you fail you have 30 minutes before you are ejected from the dungeon. If you failed to complete the mission in the 90 minutes, but do it in that extra 30 you get roughly half points.
The only way to magically get points is to screw people over. To scam them really. If you start an adventure and then leave (leaving your compatriats with a man down, and a harder time succeeding) and they go on without you, and they succeed (or get the lesser award) you WILL get points if you are still online and have not left the adventure. If you did that just once to me, you would be on my never-group-with-this-ass list. Get on very many of those lists and you will have a hard time getting groups. Now I have had folks have honest RL situations..where they LOGGED after leaving us to struggle...this, I didnt like, but didn't hold against them. RL happens. But rest assured, if you leave on some excuse, I will keep tabs (as will others) and if you never logged..your name is mud to that group.
Now I am not implying that you, adamio, would do that. Just since I mentioned how, I should give the caveat. Use the knowledge of how to avoid being scammed yourself, but dont do it.
I can't speak to the aug/instrument question from personal experience at this time.
Reys