1. Either is just fine. I usually just set or rather keep, mine on 20/4 all the time. I say the plant needs rest/darkness sometimes.
2. What size pots are you starting in? I water my pots or cups before hand and then plant. And usually wait until the pot is light and dry. You want that tap root to search out as far as it can looking for water, so if you keep water rigiht at the surface all the time it hinders it from rooting out so much. I used to have an issue with over watering so I had to learn to 'starve' them sorta. But it has totally turned around for me and works. After they have two sets of leaves I give them a 'full' watering. If you have a proper mix that is light and airy and has good drainage then it shouldn't be to easy to over water.