Am i correct in saying sdi has essentially been killed off like ahd , so won't be available much in the future ?
Market leaders tvi and cvi
But straight ip onvif still have advantage of compatibility
Get a digital volt meter unless you intend to guess , because you have allot info above , have you tried any yet?
There's no garuntee there's no faults present on the existing wiring unless you know how to test the cables
Although I think you will get stuck programming it , as above you can read it manual , mean time run a cable to every sensor point to get started and bellbox location
Com2400 leave it for now will just give you more headache I believe
Looking at your pic
Red / brown maybe positive +
Blue / black maybe negative -
Just power them seperate
On adaptors centre pin is normally + and outer is -