in our last round of training classes (last night is this friday

), there are a total of 10 dogs,and 3 of them are seniors! In our grade 2 class there were about 10 dogs, and 4 of them were different seniors! It is never to late to got into training!
Also, doing formal training with your dog will help you build a better bond, and also help to establish you as the top dog.
Not sure about the cost of trainig in NB. but some of the classes here in Ontario are around $200 for 8 week.
Also, I would start off in the lowest level of classes. A lot of what they will teach you may be review (like sit and down), but you will re-inforce and also ween of of using the treats.
Good on ya for taking the responsibility of taking care of this dog. It sounds like you have your self a wonderfull companion, enjoy!!
P.S. take lots of pics!!! the folks around here cant get enough!!!