This map was pretty annoying to play. It kind of felt like you threw some noodles on the ground and then turned that into a map. What I mean is the amount of side paths, flanks, loops, hallways and rooms led to a very confusing map. To top it off, there were zero signs, except for capture point signs, and no clue as to when we were getting deeper into enemy territory. I came across the backside of the other team quite a lot. I only saw my teammates if we respawned at the same time, but we always took separate paths because there were so many and I rarely saw them again.
You need to do a few things. First and foremost is cut down on side routes, or close and open them as certain points are captured for use as shortcuts for the attacking team. Second is put up signs. This should aid both in fighting confusion and focusing fights in certain areas.
Also I don't think I saw any pickups...? Can't say I was looking too hard.
And you aren't copying the bsp from the sdk folder, are you? That could be related to your naming issues.
Edit: AND I just realized you never answered me about the advantage to a 6th CP. I think the overall layout is decent but I am not sure about the 6th CP.