BTW, to answer your question, the "baby leaves" (the "round ones" that grew right out of the seed) will turn yellow and drop pretty quickly, it's normal, don't worry about it! As for the water when growing in soil at this stage of growth they shouldn't need more than 200ml (about a cup) every other day, it depends on the temperature and exact composition of the soil of course but as a rule of thumb this is how much they should get.
like 1