Yes, they all basically mean 'How many?' or 'How much?'. The actual prefix depends on the word class of the things you're asking for:
Saa ngapi sasa?: What time is it now? (lit. 'how much is the clock?').
Watu wangapi?: How many people?
Miti mingapi?: How many trees?
Magari mangapi?: How many cars?
Vitu vingapi?: How many things/objects?
Nyumba ngapi?: How many houses?
Nyufa ngapi?: How many cracks?
See this thread (column -zuri prefixes): https://forum.duolingo.com/comment/32745349