Can be folded with the seat unit attached (or, perhaps, some other Adamex stroller system)? If I use the Nuna Pipa, do I need the adapters?
No, this pram - not other Adamex strollers with reversible seat units are not meant to be folded with the seat attached. If you try it, it might be you will manage it, but it won't be smooth, and the whole package will be crazy bulky.
Nuna Pipa car seat compatibility-wise, Adamex prams have to be equipped with Maxi-Cosi-style adapters (some have those included in the set, some have to be ordered separately, it will depend on the shop/seller's offer, so be sure to ask there) - in these, the Nuna Pipa capsule can be attached and used with any newer Adamex frame as a travel system.
Btw, all of this is already written in the Strollberry stroller specifications under each specific stroller - just click on the specs to unfold all that is inside ;-)