Do I have to bring my own (inflatable) matress and bed-sheets and stuff?
AMAIDI Guesthouse, your homestay family as well as other guesthouses, incl. the accommodation that project organizations will offer you, will all take care of that. If you have a back-problem and you know that sleeping on a hard(er) matress will cause you trouble, you might consider taking a device that you could put on your Indian mattress to feel more comfortable. But sometimes some (local) cushions will also do.