There is a bit of extra slack in the chain, although I think the angle of the picture with the chain against the left chainstay gives the illusion that it's more slack than it is. Whoever had set it up before me left the chain a bit too long, and I was waiting until I get the new chainring to do anything about it.

Putting the rear brake ahead of the seat stays is not the convention, but it has zero effect on brake performance. I did it because the frame is old and not set up for recessed brake bolts, and it is much easier to drill out the rear side than the front, as the seat tube is in the way. As a bonus, the cable housing stop is on the right, so having the brake flipped around let me have cleaner cable routing. As a further bonus, mounting the brake in front of the stay gets it out of the way of the rack support arms that will be there soon.