I believe a 400 MH is too much for clones. CFL would be my second choice.
Topping, and tying down would be my recommendations for keeping a mother in veg, I would also use T-5, T-8 or T-12 with daylight bulbs for a mother, even if I had to buy them from a second hand store. T-12s are pretty cheap now a days though.
It is OK to use any kind of light for veg, but people (myself included) use fluorescent and CFLs for veg because the energy consumption of a 400w MH or HPS is not proportional to the result you get, this means that by using CFLs and T5s you get pretty much the same result but at a fraction of the cost, making it a much more efficient setup for small grows. You will spend way much more money on power than you would by investing in CFLs and T5s.
For clones 2 CFLs are more than enough. You are not going to get better results by using other lightning setup. And I'm pretty sure that you will harm the clones with a MH because of the heat.
Also, keep clones under 18/6 just like the mothers, 12/12 and below is only used for flowering.