3) Input impedance (without battery, in DCV) fluctuates between 5M and 7M Ohm. With battery and turned on, between 7M and 9.5M.
That reading will depend on Ohmmeter and on 869 DC range used (V or mV, and different manually chosen ranges).
If Ohmmeter creates overflow on 869, its range protection is active, and will create random Ohm readings.
I use 34465A as Ohmmeter, readings for reference:
BM869 range / compliance volt reading 34465A Ohm reading (and its range)
50V / 05.073V 10.101 MOhm (10M range)
5V / 2.6503V 011.111 MOhm (100M range)
5V / OL 11.107 MOhm (10M range)
500V / 005.02V 10.006 MOhm (10M range)
1000V/ 0005.01V 9,9993 MOhm (10M range)
0.5 V / OL 6.617M (10M range)
0.5V / OL 009.989 M (100M range)
Frank