Likely bands are loose because the wood has shrunk over the last 130 years since it was fitted to the rifle. Wood will be extremely dry now. You can do something about that by stripping the rifle down, cleaning the woodwork very carefully, inside and out, and then replacing some of the lost moisture by slowly substituting raw linseed oil for the evaporated water. When the woodwork finally expands to its original dimensions, you can seal it fairly well with boiled linseed oil and Japan Dryer.
Yes, friend Horilka is quite correct; there was information on ammunition posted here last week. I posted it. Ammunition is nearly impossible to obtain, but it can be made rather easily. You need a lathe because the cartridge rims must be bevelled properly to fit the configuration of the bolt-face. Once that is settled, you can use 8x50R LEBEL casings to turn out a short-case variety of ammunition (necks will be quite short). This might sound sacreligious, but you must remember that the Lebel cartridge was a straightforward development from the Krop rounds already in use in the French military. If you don't plan to make your shooting ammo from Lebel brass, you can start with .348 Winchester and go from there; it is a longer and much harder route but it will get you there. You can get Lebel brass from site sponsor TRADE-EX (Gray ad in the block at top, 2nd row, 2nd in), by the bag.
There are a couple of fellows on this forum who have rather extensive experience loading for the Krop. If none of them post in quickly, I would suggest (once again) using the SEARCH function to track down some of their hard-won information contained in older threads on THIS forum. Alternately, you can buzz over to milsurps dot com, take out a membership there and query some of their people. Just don't be too surprised if you run into a lot of familiar names!
Your missing "bullet pusher" is called a MAGAZINE FOLLOWER and they are not difficult to make if you have access to a lathe. Your missing SPRING is called the MAGAZINE SPRING; it was made from coiled music wire which you can get at a piano store. Likely somebody will know the correct diameter, number of coils, and length to which the spring is SET. Music wire commonly is sold in llittle rolls of 1 pound of wire. It is sold by its diameter in thousandths of an inch. There is a LOT of very thin wire in a pound. Don't ask me how I know!