If it is a tall one, yes. The Beechgrove Garden folk did it last year and it looked good.

I do it. I wind lengths of thread in a spiral round the obelisk to tuck the plants behind as they grow or else they escape into the other plants. They don't seem very keen to use their tendrils to hang on to the obelisk to begin with.

Ditto to Steragrams idea. I use garden wire.