1) AFAICT, you just subtract the ongoing damage from the total as if it was a static modifier, e.g. an attack that does 1d8+5 is equivalent to an an attack doing 1d8 + ongoing 5.1. How are attacks with ongoing damage accounted for in the new monster damage equations, or aren't they?
2. How are attacks that have nasty riders, for example, dazed, stunned, pushes, etc., (especially, multiple nasty effects) accounted for in the new monster damage equations? Or aren't they?
3. How are standard at-will attacks that can be used twice in a turn as a standard attack (for example, Double Attack) accounted for in the new monster damage equations? Or aren't they?
2) Just compare the damage expression against the old table: what column is it closest to? Then use the same column in the new damage progression chart.
3) See 2), though I'd be surprised if you ever find it uses a different column than the low damage one for standard monsters. For elite monsters it could also be the std damage column.
So far I've found changing the damage expressions is pretty straightforward.
It only gets more complicated if you're looking at a monster that deviates from the average attack bonus. Hobgoblins are an example for this. Apparently, some monsters are supposed to trade-off damage potential for better accuracy or vice-versa.