The setup with the 125w's looks ok but I dont think the single 125w would be enough for good flowering. It might veg ok but I like your first idea of using multiple smaller CFL's for vegging and then going for a 400w hps for flowering. Heat is going to be an issue with the 400w so you will need to do some ventilation planning.

Trust me, you don't want me as a mentor, lol. I am deadly to indoor seedlings....my tendency is to care for them too much and it has taken me a long time and many dead or stunted seedlings later to figure out I don't need to water them everyday or even every other day. There are many many people here who will be happy to share their experience and help you along the way as your grow progresses and your questions come up. Just ask!

The forums are full of grow logs and guides...just start reading some of them and you'll be well prepared.