I had that same problem with my 93 acura. There ended up being a pinhole leak in the radiator where the plastic top met the aluminum and i was going through a whole jug of coolant like every couple weeks till i got a new radiator.

A little water on the ground is normal condensation if you've been runnin the a/c for a while, but it sounds like you have a leak too probably in your radiator. As long as your car isn't overheating there's no huge problem. try putting a bottle of 'barstop' (i think thats what its called) in there-- its a liquid with suspended copper that fixes the leak usually. Thats what i used until i saved up enough $$ for a new aluminum radiator and it worked alright. good luck