If i understood corectly i can use a central (+)cable and as (-)the frame?(theoretically as a huge cable?)
Correct. I used the frame as the negative lead as much as possible. It saved me a lot of time and effort, plus added reliability and provided for practically unlimited current draw on the negative side. Look at the entire circuit as one wire - the longer and thinner it is the bigger the voltage drop. By using the frame, you practically shorten it by half.
Do you think that my goal to eliminate OEM wiring and rewire ignition/cdi etc. is possible?
It's possible, but not necessary, IMO. All you need to take care of is the wiring for large draw items such as headlights and any other electrical stuff you want to add. OEM harness is good for everything else.
In your posts you mention voltage drop over wires.Assuming that Suzuki has calculated v.d. in oem wiring...
Suzuki terribly miscalculated the voltage drop for the headlights. Other components are not so critical or sensitive, plus they have much shorter wiring to them (CDI and ignition are closer to the battery than headlights and draw much less current).
If i attempt to rewire ignition,will sorter wires and difference of v.d. affect the performance of these critical components?Is there by any chance a way to measure it?
It probably won't make any noticeable difference. Voltage drop is relatively easy to measure. Disconnect all other circuits except the one you measure for, measure the voltage at the battery and at the device when powered. You can experiment with a headlight bulb connected to the battery via a 6 feet of relatively thin wire (say, 14 or 16 gauge) to get an idea. Then connect it with the same length of 10 or 12 gauge and measure again.