Instances: how do they really work?
I like the fact that you will only need to rename the prefix in order for it work perfectly in-game. By creating a prefab of an instance you can have automatically named instances with the _&i option.
I work a lot with instances (mosifications of the stock instances) and as Lp said they have the big advantage that any change you introduce into them will be shown in every map you use them. That's why I hardly collapse them in any map except when I have to tweak them a bit to fit some of their settings into a certain place in a map.
The most interesting part to me is to mess around with the inside inputs/outputs and then target them to be fired by the func_instance_io_proxy. I think this is an awesomely useful system.
useful tools and stuff here on TWP 
[spoiler]
[/spoiler]
Well, could you help me again?
A map created on PTI has both elevator as instances, and they use that teleport entity. Well, I need to move that entity a little, if I collapse the instance, and move the entity, will it mess up everything?
A map created on PTI has both elevator as instances, and they use that teleport entity. Well, I need to move that entity a little
I'm not sure about why would you need to move tha entity a bit. Anyway, if you're referring for example to that entity that teleports the player to the elevator right in the beeginning of each map so the player can start moving altogether with it, that entity is a point_teleport and you have it right at the bottom of the elevator prop into the instance elevator_arrival_logic:
You don't really need to collapse it, simply edit the instance, move that entity and save it under a different name for example. Anyway, I don't think you mess up everything if you collapse it though. But I'm not sure which names will hammer give each entity inside these after collapsing, check that out carefully because the arrival_elevator_logic and the elevator_entrance instances work along firing i/o from one to the other.
useful tools and stuff here on TWP [spoiler]
[/spoiler]No no, I need to move the point_teleport that teleports the player into that little room which says the number of the level right before entering on the puzzle area. It's because I've added another room, and I need to put it between the elevator and the main level itself...
Just move the room with the level number back and add the room between that room and the map and you should be fine.
But unfortunately it must be between the elevator and the level number room, can't be after level number room. I'll try to figure out something here, may'be i'll create a instance of my own. Can you use like 3 instances, save it as a map and use it as single instance? Maybe this will help me a little.
Then you need to go into the instances, remove the world portals and doors and link them together with normal doors manually...