I run my anvil units 5 wide, mainly cause I think 5 is a nice number, but it also gives a extra "free" wound in each rank before you lose the rank bonus and you can easily redress to a larger front age since the most models you can move anyways is 5. You want the ranks as the main use for anvils is the static combat res. They are going to lose combat, but with the high leadership you will be forcing the opponent in a position you want, and that is stuck where they can't move.
I run my missle blocks small, minimum size, I find large frontage for missle units super ungainly. It is hard to wheel, hard to move, the opponent can easily get cover, and they are easier to charge.
Finally, I run my hammer units about 6-7wide for the attacks. If possible give them drilled as it helps with better positioning and movement. I hang around just behind my anvil units, 1" or 2" and off to the side for flank charges.