Looks very good. I am liking those samsung boards!
16-8 will hurt nothing. I had some vegging at 18-6 and changed it to 12 12 but it was really 14 10 because i didnt have my glasses on. Wow did they get big. They vegged even longer than expected.
The hours you run it really depend on where you live. Where i live it is best to time it for offpeak time for hydro costs. BUT I do like to pop in and check in the morning and who wants to get up at 6 am to do that. So I go 9 to 9 so i have some time either side to admire them and breath co2 everywhere (the co2 was a joke).