12V Battery Connect Solar Panel and other appliances

Hi,

Ok, this might seem a very silly question (please be kind).

I am replacing an old 12V battery that has the following electronic equipment attached. (see wire diagram). I want to make sure that I get the order of connecting the (+) and (-) correct.

Wiring
Connected to Main Terminal on 12V Battery:
1. 8hp Diesel Engine (battery used to start the engine)

Connected to Screw Terminal on same 12V Battery:
2. Direct Connection
2.1 Bilge Pump (Fuse and separate On and OFF Switch, Bilge Pump always ON)
3. Main SwitchBoard
3.1 All lights with fuses
4. Second SwitchBoard
4.1 VHF Radio
4.2 Radio (AM/FM)
4.3 12V Auxiliary Power Outlet
5. Solar Panel

Disconnect
When I disconnect the battery I turn both the Main and Second Switchboards OFF and the Bilge Pump OFF.

I disconnect the cables (1) from the Main Terminal (-) negative first and then (+) positive, making sure I don't short circuit the battery by touching both terminals with the metal tools (wrench).

I then disconnect the Lugs (2, 3, 4, 5, 6) from the Screw Terminal (-) negative first then (+) positive.

Reconnect
I then do the same as above but in reverse order connecting (1) to Main Terminal (+) positive first and then (-) negative and then (2 ,3 ,4 ,5 ,6) Screw Terminal (+) positive first and then (-) negative.

Then I turn the Bilge Switch ON and Main and Second Switchboard.

Question
I purchased a new solar panel with MPPT controller and it reads in the manual to connect the MPPT controller to the battery first before the Solar Panel. It says to connect (-) negative first and then (+) positive. I do have a 20A ANL Fuse in between the MPPT Controller and the battery and a 10A MC4 In-Line Fuse between the MPPT Controller and the Solar Panel.

A. Why do I connect the (-) negative first and then the (+) positive for the MPPT controller?
B. Did I incorrectly wire the above Screw terminal equipment before connecting (+) positive first and then (-) negative?
C. SwitchBoard is OFF so it should protect the equipment?
D. Do I connect the solar panel to MPPT also (-) negative first and then (+) positive? Why?
E. The MPPT controller also has a LOAD connection 10A but I saw that the VHF when in use draws 5Amps and the Bilge Pump can also draw close to 5Amps - do I risk overloading the LOAD connector (turns off automatically over 10A as per manual). Do I simply not use the LOAD connector and continue with my current set up using the SCREW Terminal.

Ok, this is a lot of questions but I hope all makes sense.

Please be kind :)

My 2 cents as well - the main thing is to connect the MPPT controller to the battery first before the Solar Panel then you can connect to the panels. The controller needs to have power to read the panel input. It doesn't matter too much but it's a safety thing to connect -ve first & it doesn't hurt to do what they say.
I don't use the load function at all on my controllers but everything from the batteries - like your diagram.
Definitely leave your (fused) bilge pump on - all the time!! So, have it bypassing your main ON/OFF battery switch.