Hey,

Ok lets see if i can help, from what you've said i assume your plants aren't very old (around a week or two?) with only one or two sets of leaves? If thats the case, it just sounds like they're stretching for the light and the weight of the leaves has bent the long weak stem. What you need to do is replant getting as much of the stem under the soil (but not any leaves) that'll give it more strength, you need to make sure the lights close enough to avoid any more stretching.

Watering and fertilizing, again this varies with age, if they're young seedlings i'd probably water a little every 2-3 days, they don't need much water at that age. You don't need to fertilize for the first month in my opinion, and when you do start fertilizing introduce it at 1/4 strength and build it up slowly.

No idea where the mystery plant came from lol

I wouldn't use fertilizer on the leaves myself but i couldn't say for sure if this would do any harm. But if you do spray even with just water it's best to do it when the lights have just gone off.

Good luck!