Disconnect starting and house battery

[Sir Traveler]

I have few questions regarding which battery to disconnect in the following scenarios:

1- I am replacing the starting battery on my Ford F-53, should I just shut off / disconnect the starting battery? Or disconnect house batteries too ?
2-I want to spray battery terminal rust protector on both chassis and house batteries, should I disconnect both in the this case ?
3- I want to start the RV (while in place without moving it) , should I disconnect the house batteries ? or just turn off the RV Park electric box ?

Thank you

[twinboat]

1 starting battery, with shore power off.

2 just spray away, unless your removing terminal to clean them.

3 start the RV, no need to disconnect anything.