Grammar!

1. Neither Alan nor his friends…intend(s): The second part of the nor is plural so the verb needs to be plural. 
2. For we citizens -> Us (prepositional form)
3. The man in the cereal advertisement, who(m) everyone in our town knows as Mr. Potts: Whom because it is the object
4. You may sometimes find it effective to cite the views of an authority with whom you disagree, (and you use), *might, can* Since this is hypothetical, it needs to still be in that same side
5. so absorbed (and thus) so absorbed that (idiom) 
6. The high school teacher, nearing retirement, observed that students became more spontaneous  over the years while he had been becoming less spontaneous:  (Both sides of while has to be had become)