Is the phrase "as well as" treated the same way as "and" as far as making a verb plural? For example: The dog on the porch, as well as a cat in a tree, were intently watching the neighbor grilling next door. Is this correct? It would seem wrong to change "were" to "was". Should I leave the commas out?

That's a really great question. The answer is no. It's not the same. So:

The leader as well as the gang members is going to prison.
The leader and the gang members are going to prison.