Hiya,
If he's living indoors then there is no need for litter all over the base of the floor. Just use a litter tray - which you can fill with either litter type. Rabbits tend to like some hay on top as well as they like to munch whilst they poop.
You might like to add vet bed or carpet to the floor just for some grip but anything else is just likely to end up all over your house
You'll also find that just having litter in the tray will help minimise matting if you're getting a lionhead.
Indoor cages provide a good base but rabbits do grow quickly! If your rabbits is going to spend most of the day shut in then you'll need to think about upgrading e.g. attaching puppy panels to make a run. Alternatively you can bunnies proof a room and leave the cage door open.
When you're supply shopping other things you'll need are:
water bottle (bowls in cages just get messy but are good if they have the run of a room)
litter tray (go for high sides e.g. a cat one) otherwise they purch on the edge and wee over. They also tend to dig
Toys - bunnies are like rats in that they need a lot to keep them busy
a carrier (cat sized is fine) you'll need this to get to the vets and safely home. Solid solids are best so they feel secure.
Avoid processed looking treats and look for natural type ones (becoming more poular)
food - you'll need to check what he/she is currently eating and feed the same brand as sudden changes are bad for bunnies. Plus you'll need lots of hay too!
I hope that helps!
Tamsin