For the Non Electric 4 full time users will commonly empty a composting container 6 times a year. In some places it can go out with your garbage but if in doubt what to do, ask your local health agent. Yes, put in the starter mix that comes with the new toilet. Then you will make additions of starter mix or peat moss or other high carbon materials to keep it going. These require very little maintenance for the vacation place and it increases mildly with more use.
Some people hire services to empty humus for a small fee.
Life on this planet is maintained by the fundamental processes of consumption and excretion. The culture of consumption is highly refined while the resulting process of excretion is considered only as something to be hidden away and filthy. This has lead to our culture's misuse of our soil and water resources to accomplish this. While we waste these resources their resultant polluted condition is always increasingly apparent. The first waterless toilet was built in Sweden in 1939.