I'll let someone with more experience answer your question regarding the growth, but here is a link to a great video by Paul Zimmerman on how to train a rose onto a trellis. He also has a good video on how to prune a climbing rose.

I'm expecting two new climbing roses myself soon, so I'll be re-watching those videos. Enjoy those roses!

Here is a link that might be useful: Training climbing rose-Paul Zimmerman

On most all roses as the wood ages it will get a darker bark like look to it. The older the cane the dark it will be. Those dark canes on yours are probably the oldest ones. As long as there is growth coming out of the cane at some point it's still alive and healthy. If growth further up starts to die off then there is a problem.

Paul's videos are wonderful so check them all out!

I love how funny Paul is. When he jumped to smell those roses. LOL!