OK, couple of things:

1.  0.3" Belt and then as much bulge possible without losing speed is what you want for KM.

2.  Gneisenau CAN be Armour Whored but not these days.  Using 11" guns (might have to drop the rear turret) the Gnei can fit a very nice amount of armour, enough to bounce most BB123s and the worse penetrating BB45s (mainly KM).  But these days, there are so many large ships around that you are going to suffer horrifically to actually get attack, this isn't like the old days where you could play an AWed Gnei and do alright because you never saw a BB5...

3.  The O1 is actually a better AW than the Gnei, I used AWed O1 for a bit with the 11" and it was a good laugh, but it is slow and cumbersome and only good when the enemy comes AT you, once the enemy starts to run away you are too slow to catch up.

My advice is to forget AWed KM ships, with the Gnei you have very nice AA, use it.  Stay behing the battle line and use your AA, also use the 15" guns in GB as they are easier to use and better than the 11".  Stay behind the battle line (But CLOSE to it) and AA every enemy plane in sight, and when you are 100% sure you can't be seen rush in, fire a salvo and then rush out when a scout gets near.  That is the KM way.

0.2 should do the job instead of 0.3

rushing ahead of the main line (picking 2nd spot north/south at deployment) is what i usually do with the gneis.

if you try to hang back until the main line comes into battle you should be able to get a couple of shots off before getting shot, mainly because the enemy is shooting BB4/5's further back.
it does requier a close to speedcap setup, so it probably doesnt work to well with an average at lvl crew.

nope, i asume the 1 point of armour protection should be enough,
i believe 0.3 doesnt give any noticable difference in AP/HE raise over 0.2 in the armour screen

would that go for all KM ships, or all overall ships then?