• Brake Pads: A company called EBC seems to be the leader in the motorcycle disc and brake pad world. If your rotors are warped, the EBC floating rotors give far more effective braking, and are less expensive that OEM units.
• Brake Fluid: This last recommendation will be the most contentious, because it is not approved by BMW. But I'm fairly sure of 2 things: 1) You're fully capable of doing your own research and making up your own mind. And, 2) I'm fairly certain your 1992 motorcycle is well out of warranty.
The most danger your bike's paint job faces is not from riding, but from DOT3 and DOT4 brake fluid. There is another brake fluid choice (used on about 98% of Harley-Davidson motorcycles) called DOT5 Silicone. Being silicone-based it will not harm your paint, but neither will it mix with standard brake fluids, so the time to convert is when you take the brake system apart to replace the hoses. I've been using this fluid since the late 70's in Honda, Lockheed, Brembo and ATE motorcycle brake systems without mishap. You may also wish to investigate it's use. Just add it to the long list of other non-BMW approved devices (third party alternators, electronic regulators, LED bulbs, non-OEM shocks, AGM batteries, un-approved tires, etc.) already in use on your bike.