Limitations of integrating 3rd party content

[Merion]

There is some free stuff around already and the content market is to come sometime in the future.

I haven't played around with import or export yet, but what I gleaned from other threads is, that there are a few limititations to a realm once stuff has been imported. Like not being able to export anything or copy the realm or such. I would like to integrate a few things from pre-made content, but if I have sacrifice any priviliges over my realm, I'll refrain from that.

Could anyone please be so kind and tell me what exactly are the restrictions I have to cope with, if I import some things? And is there a difference between official things like "we be goblins" and player-made content like the 5e NPCs that have been posted recently? And if so, how do I know beforehand?

Any enlightenment would be very appreciated!