The curve above the brake looks like it is crimping down on the cable, so yeah, it is too long. The curve coming out of the cable stop is about the curve that you want going from the stop to the brake (but curving down rather than up). And it is ALWAYS better to be slightly longer than shorter, you can all ways cut it if it is long, but too short and you need another housing.
The best way to measure the housing is with the cable out. I would drop the adjuster almost all the way down (leave a few threads showing so you can adjust it down if you need); remove the cable, chop an inch or so (from this shot I would maybe even do 2 inches), replace the housing and look to see if there is a gentle curve. Chop a little at a time until it looks right, then put the cable back in and tighten everything down.