I'm sure this is earlier in the thread, but:
TD Garden Legendary Transformation | TD Garden
The "Back Row Bar" on the 301-side will be there, as well as expanding loge and balcony concourses. They're both listed under "Starting next season", which is fairly vague. I seem to remember reading or hearing something that made me think, "Oh, there's more space starting at the start of 2019-20", but I might not have been reading the fine print. And, of course, as with any improvement project, there's bound to be delays. When they redid the loge (summer 2014?) and the balcony (summer after that), there was definitely some residual messiness during the preseason games.
As far as restrooms, they do say they're putting in "additional restrooms throughout the arena". Again, it could be anything from a Port-O-Potty up on 9 to ACTUALLY doing things to solve the restroom issues. (Fun experiment: It's possible to go to the bathroom and not miss any action if you time it JUST right during a TV timeout, and you're in 304.)
They've already started some very preliminary work - if you look on the 301 side or the 1 side, they have some of that...I want to call it particle board?...set up. First noticed it during the recent 6 game homestand.