Will this rod hold heavy curtains?

It is a metal rod meant for medium-weight curtains. Over a long span, add the center bracket and use sturdy wall anchors, since heavy drapes put the most stress on the middle.

Does it work for sliding glass doors?

Yes, the adjustable length covers typical sliding-door widths. Check that your curtain panels clear the floor and that the brackets land on studs or solid anchors.

Can I use it with clip rings?

Yes. The rod is a plain round bar, so clip rings and grommet panels both slide on it. The cage finials unscrew for loading curtains.

How many brackets come with it?

Long adjustable rods usually ship with three brackets so the middle can be supported. Confirm the bracket count before installing on a wide span.

Will the bronze finish match oil-rubbed bronze fixtures?

It is a brown bronze tone, so it sits close to oil-rubbed bronze but may read warmer. Compare it against your other hardware before committing to a whole room.