Avoid Chinese discs, it's false economy.
The rear disc is a hell of a lot cheaper than the front two, so just buy a decent brand.
As for the bolts, be prepared for a shocker getting them undone.
Because the disc is fixed to the wheel rather than being floating, the heat transfer tends to fuse the bolts to the hub and they can be a nightmare to remove.
Personally i would say stick to OEM bolts, although others will undoubtedly have their own opinion, but either way buy them before attempting to remove the old ones so that they are on hand.
Plenty of heat, and swearing, seems to be the preferred method of success on getting the bolts to budge.