I don't think he ever fully recovered his speech after the stroke he had.

Kelso is actually on the sign, just not shown in the first few when they're walking up. As they walk away, you can pause it and look at the rest of the sign and Kelso and Cox are there.

I've read this recently too and I can only wonder if the freefall that was later seasons of Heroes has tainted Loeb and his desire to do anything with any kind of arc.

Remember Estes coming in and telling the VP that they had sourced the explosives used in the park bomb to Saudi Arabia?

If there's a mole, I'm pretty sure it's Galvez. He was tasked with watching Carrie, he "can find anything" and Middle-Eastern passing as Hispanic could work.

One of my favorite parts of the show is when Ava has to interact with Amy. She always treats her like that person that's your rival but you have to be civil to.