Speed 0 does really make sense for these, they are
way too big and heavy for their crew to drag by hand without a vehicle. Look at the model and see whether you think even three men could feasible pull such a weight of metal:

I'm not sure that transports for them should be mandatory - if they're not then it forces you to make a decision between keeping them in one place all game (likely behind a fortification) or adding light transports that bulk up the formation size but are very fragile light vehicles and go down quickly and are vulnerable to both sorts of fire (quite possibly discouraging these formations use in infantry companies at all). If you have seperate units of them and need to bulk them up to avoid popcorn perhaps add either the few transports
or the same number of infantry stands.
I don't see the need to have to make support formations necessarily 4 just because that's the maximum numbers in W40k - represent the units and the feel of the army correctly for sure but with units sizes the much more important thing is doing what's right for epic gaming and not sticking obsessively to what's in W40k. The unit sizes are up to 4 and not required to be 4 in W40k no? And it's not like the W40k lists and rules really represent the background sizings or unit dispositions all that much anyway either and nor do many epic lists. Also with the way barrages work in epic unit size 3 means these smaller barrage weapons would be
better with twice as many barrage templates hitting twice the target area that the larger more powerful weapons like the Basilisk or Medusa guns - surely this doesn't sound right? I vote for keeping them at 3 myself.
And for the second time please can you fix that download or host it elsewhere or something E&C? I have still never been able to download it and am meant to be playtesting it Sunday.