Engine problems! PLEASE help!

[Apolan]

i dont know exactly where the pinging sound is comming from; but it seems most likely its comming from the bottom. possibly from the crank-rod bearings. or maybe from the upper piston pin.. the sound seems preety much like mechanical-banging. its just very confusing why this sound depends on ignition timing. acording to that it moves up or down the rpm range.. when my timing was off there was no pinging in idle or up to some 3500 rpm.. now when i set it correctly it can be heard just above idle (1200) and up.. (getting stronger and stronger as the rpms increase.

the no 1 spark plug is no longer black (i guess it was black just because that oil problem in roundabout, burning oil - blackening the plug). now all pčugs are equally whiteish.. what could that mean?

how do i check oil pressure? and what is that gauge on the dash for? oil pressure or oil level? it is constantly on LOW - but when i check the level on that stick it is all the way up!