what are your water parameters, why is it you are looking at a wet dry?, you should be fine with the equipment you have, especially if you have a dsb too,
as for the mandarin, be cautious, you really should have a larger tank with a lot more lr for 2, they will probably deplete your pod population, leaving both of them to starve(not that it can't be done, but it is unadvisable IMO)
and the ff, study them before buying, they are a hearty fish, but can be difficult to keep with other ff, just make sure the 2 you are purchasing are getting along well
HTH