I'm so sorry, what did you end up doing?
I've seen this before. Someone repointed your bricks with portland instead of lime cement. They might have also sandblasted or used a non-breathable sealant. On the upside, It looks like your mortar is in perfect condition! Of course, that's not supposed to be the way it works. I've learned that mortar is supposed to be a sacrificial element of your masonry. Houses move a lot more than we think and mortar is supposed to crack before the rocks or bricks. If they sandblasted, they removed the harder outer "fire coat" which normally keeps excess moisture out.
You really don't want to double down on the waterproofing. When your house was built, bricks were a lot softer, partly because they were fired at a lower temperatures. The lime mortar lets any moisture that's absorbed move back out of the face of the building. Google "spalling bricks."
https://www.nps.gov/tps/how-to-preserve/briefs/2-repoint-mortar-joints.htm
This video shows him shoving a lot of mortar in but that's the first step--you have to compress it next. His videos have horrible sound in places but it's good info.
https://www.youtube.com/watch?v=TGs6GhGZiso
https://www.youtube.com/watch?v=4vV5-vB4fRw&index=2&list=PLb5oz8FOCSxhcVXcfEsXHixIn-qcG_pgB
