How do the decentralized clouds work?

Reading up some on cloud tokens. Sia, Storj and Filecoin.

Curious on how reliable it is when you rent storage place of regular users. Anyone who used DC++, eMule and all the others in the past know how long it can take to actually get your files to start downloading. Know, better hardware/net, but still.

I know it splits up files and save multiple places. It is all fine and dandy, but do it need ALL the pieces to get the file? Or do they work in some RAID'y way so it can be rebuilt with a few missing?
Lets say if I rent out a few TB's now from a couple of locations. If I suddenly need the space again and have to stop renting it out, is there a chance some poor lad lost his files?
If I need to rent myself and upload 100GB. Is thre 100GB usage on the network or do it multiply for redundancy so it actually use 300GB or something? Know I still pay for 100GB only