'66 valiant questions on parts....that fit.

Working on '66 Valiant, stroker, dual quad on an offy.
Looking for nice bumpers. Found '65 bumpers. Will they fit '66? Also looking for taillight bezels. I believe '65 and '66 are same.

Living in Florida and want A/C. Have some parts, need to finish up with compressor and hoses -going under dash. Who is the best source for online purchases for this sort of thing?
Finally, when I find items I need for sale on this site I don't know how to contact the seller. What is PM? Sure would appreciate some help. I am not especially great with computers but seems like this modern world doesn't give you much choice.
Thanks Folks.