1. Sorry. I should have asked where is it leaking from.
2. If the central spout only when one or both taps is on, then it will be the spout which needs removing.
3. If the central spout with both taps off, then one or both taps will need new cartridges.
4. If from one or both taps, then one or both will need new cartridges.
5. I'm assuming they are 1/4 turn taps.
6. If either cartridge needs renewing, the water to that tap will need isolating, or you'll get wet.