In case of I found frozen caliper, I heard it can recur even I push the piston back. I read "If the holes in the caliper where the pins pass through are worn oversize, then a new caliper and pins are required. Except in cases of early failure of one caliper, calipers are often replaced in pairs, the logic being that if one caliper has failed, the other one is not far behind. It all depends on the nature of the failure."
So if I decide to replace the caliper,
1. do I need to replace the caliper bracket where the guiding bolt screw into? No
2. do I need to replace caliper on both sides of axle? That is recommended
3. do I need to replace the guiding bolt as well? Not unless it has a deep notch in the body
4. do I need to put brake grease on the guiding bolt as well? Answered in previous posts, but also check the rubber guide bolt bushings for excessive wear. The bushings can be pressed in place.
5. if I need to flush the brake fluid and looked at bleeding brake
I worry that my only bmw jack is not up to the job. What's recommended here if I only have one jack? You can bleed one corner at a time if you don't have jack stands or another safe way to support the car with all four wheels off. BTW, you will need a small (approx. 9mm) box wrench for the bleeders.
6. where is the bleed screws? The one connect to the caliper piston? As shown in the pelican article, on one corner of each caliper, facing upwards with a rubber cap.
You won't need to measure anything if you are just installing some new pads/rotors and doing some brake bleeding.