1) B is 0.01uF,50V,+80%,-20% axial ceramic capacitor.

2) I believe your statement is true. The +/- are the tolerance ratings.

3) Do NOT confuse the "SR" with the "SRC" components. SR are network resistors. SRC are network resistors with capacitor. SRC components are no longer manufactured but you can leave off the capacitor component and use 9-pin,8R network resistors. See http://www.pinwiki.com/wiki/index.php?title=Williams_System_9_-_11#Repairing_Alkaline_Corrosion for more details on this.

4) Yes. A 6821 is a 6821. Does not matter what company manufactures it.

5) Those letters are usually codes for certain things. There are sometime letters between the numbers (e.g. 7402 vs 74HC02 vs 74HCT02 vs 74LS02) and those may make a difference.

Good luck with your repair. I would advise you check your traces before putting any component back on the board as it's easier to see and fix the traces without components on the board. You also do not want to unnecessarily undo any work you have done. Most of all ... enjoy the ride. It's often a LOT of work but when it finally works it's satisfying to bring a board back from the dead.

That (by hand) manual correction is INCORRECT. Here's the reasoning (and logic) for that conclusion.

System 11 (used in High Speed and Road Kings) has SRC6 and it's listed as component 87 in the component list. It is 8R,8C,10-pin,1kOhm,0.001uF. It's used as a pull-up resistor on the switch columns (drives).

System 11A (used in PinBot among others) is a System 11 board with diagnostic LEDs instead of the 7-segment LED display. It should have SRC6 just above the 1J8 connector.

System 11B (used in BK2K and Whirlwind among others) is a System 11A board with connector 1J9 removed. Components in the switch matrix area have a different layout and SRC6 was removed and replaced with discrete resistors (R138-R145). It's electrically equivalent.

If you have a System 11A board you will need SRC6 as a 8R,8C,10-pin,1kOhm,0.001uF network resistor. As this is no longer manufactured you can replace it with a 8R,9-pin,1kOhm resistor network. Leave pin number 10 disconnected (fill it with solder).