Yocum should not follow N Face R Gully. N Face R Gully is WI and Yocum is rime ice. If your goal is Yocum you should climb mutliple variations on the Reid Headwall first. Some time on Illumination (W Ridge or similar) would be good too.
I would go over the top and climb Elliot HW before you climb N Face R Gully, it's logistically easier.
RE WA climbs, here is what I've experienced, but as MThorman describes above, conditions fluctuate a lot...
Colchuck NEB is mostly snow, if you can climb Cooper Spur or Reid HW on Hood you'll be more than fine.
Triple Couloirs stacks up like N Face R Gully... maybe a little harder crux pitches, if it's in good shape.
Kautz is more glacier travel, if you can do that and climb some ice + have the fitness you'll be fine. Sunshine route might be a good trainer on Hood, but by no means a pre-req.
Baker N Ridge is like a combo of Cooper Spur exposure with N Face R Gully schrund/ice climbing (but the ice is glacier ice so different, usually pretty easy ice climbing if you want it to be).
I assume you're closer to Hood if you want to focus on it this much?