When I have planted new climbers, I let them grow as they like for at least one year. This way you get some structure to work on. I think this helps when deciding the overall shape / place you want. the rose to climb.
If its a rambler then you only need to prune out the dead bits. Strange that it didn't have a name though.
What exactly did you have in mind when you said "infected"?
I am aware in companion planting the support plant can keep away certain insects which can harm the principle plant, keep disease etc. at bay.......bit limited in my knowledge about these matters
In summer I just plant marigolds around my Roses, I think it helps with some flying pests. Otherwise, I just spray regularly to avoid black spot. and those sort of problems.
The other thing I do is make sure the roots don't get dry - because I think dry roots can cause Mildew
Your rose, if it is a rambler, will probaby far outgrow any companion plants. They get very big. However, they do tend to become a bit straggly at the base so you could putin a clematis to fill in the base. Pick one that flowers at the same time and has a colour that suits the rose.
Will it be ok to cut back the rambler if it grows too much......will it still produce flowers ...
They flower on branches that come off old wood so if you cut it off in Year 1, you don't get 'em in Year 2.
I am looking of a white climbing rose preferrably scented what do u recommend?