i know this was posted already but i couldnt find it.

some maps can lead to problems if placed directly in the \data\ folder, like some of the Q3 mappack maps, so how to start a map thats inside the \dlcache folder?

copy them to the data folder. no no kidding. if the maps dont work in the data folder but works in the dlcache folder something else is weitrld, like you being required to have more than that one pk3 to make it work

anything in the dlcache folder will only be loaded upon request from the server iirc

Well you could issue a download request manually to load the pk3 file, but it would be more helpful if you post a list of pk3s that make trouble when added to data/ (esp. the q3 map pack should pose any problems).