Tightening sequence isn't super important. Start with the inner bolts (middle of manifold) and work your way out. First snug them, then torque them, then double check then to ensure proper torque.
Best advice we can give you on this part is to use a dab of sealant on the lower 10 threads of each bolt for the LIM as you put them in. That will keep any seepage from occuring later down the road.
On the cooalnt elbow, yes you can reuse it. In your new upper kit will most likely be new o-rings that fit it if they look like they need to be changed. After only a month, I doubt there is any need to even do that.
00 Regal GS: All kinds of cool stuff.