I take it you mean install 10-15mm of extra oil in the fork, is that right?
No, the oil height is different. Installed preload is the amount the spring will be compressed when the fork is assembled with the preload adjusters all of the way out.
Oil height of 135mm does account for the extra (I think stock is around 150mm?). When you are filling the forks, with the spring out and the upper tube fully compressed into the lower, you'll want the oil height at 135mm below the top of the tube. Before measuring, you'll need to pump the cartridge to get all of the air out of the chamber.
I just turned the rebound adjustment all the way to soft (counter-clockwise), then backed them back out 1 turn each (clockwise). For some reason my left rebound adjuster would go out 2 turns clockwise from full soft, but my right adjuster would only go 1-1.5 turns before stopping. Weird, but that's a different story.
How do you like those .95 kg springs? Are they a bit too stiff or just right for you?
The adjusters won't necessarily have the same exact number of turns between the 2 forks; it depends on how the forks were reassembled. You can make them consistent when you put them back together; it's not hard. The only way to be consistent in getting the rebound setting the same between the 2 is to start from fully closed (clockwise), and back out the same number of turns from there.
I like my .95 springs, but I can't make a fair comparison because I have them in f4i forks with different valving and lighter weight oil. I was able to set my sag correctly, though.