do like you are "water then wait couple days too dry them then water again plants looking ok 1 drop per gal ST sounds good
youg seedlings are very easy to overwater be patient if it takes 3 days or 4 days thats what it takes, it all depends on conditions in room heat/humidity
light i would buy more light if your that broke instead of the FF/OC soil and no you can't get it at HD/LOWES