Howdy SOF.
If you enjoy catching someone parked on an airfield 5000 meters below you or just like being able to drop an egg on your target and hit it, then you'll enjoy this. It looks like you already know these maps are somewhat based on ISA (International Standard Atmosphere) and also that temp rises by .0065 deg C per meter. Also, that 15 deg C is the temp at sea level for ISA normal, at least for one, so I don't really need to go into any detail about that. (I believe there is another ISA that starts at 0 deg C, but we'll ignore that one)
So, on to one of the formulas. While looking at the IAS/TAS chart, I was able to derive a formula that came up with their numbers:
(IAS * .0657 * (ALT/1000)) + IAS = TAS
I quickly realized that this formula didn't take into account changes in OAT (Outside Air Temperature) and it wouldn't have been on a curve...so I modified it. What I came up with is this:
((IAS * .066 * (ALT/1000)) + IAS) * (1 + ALT/100,000) = TAS
Using real numbers, let's say you had an IAS of 260kph and an (indicated) altitude of 4850m. The equation would look like this:
((260 * .066 * 4.850) + 260) * (1.04850) = TAS
In operation, you would multiply the 260 by .066 then multiply that by 4.850, then add the 260 to arrive at a temporary airspeed. You would then multiply the temporary airspeed by the 1.04850 to arrive at your TAS.
Now, here's the deal. The .066 factor is only for some planes, like the B5N1 Kate (my favorite bomber). Russian planes like the Pe-8, the IL-4 and some others use .084. The He-111 H-2 uses .026 and the H-6 uses .046. Also, this formula is used on other maps where the temperature is different (above or below ISA), but it's calculated differently. Namely, you'll be calculating for density altitude. But I'll get into that later on.
I tested this formula by using the Gulf of Finland 1 (summer) map, since it was ISA normal. I used the Island of Lavansaari/Moschnyi as a base and put several air starts in grid AV-11 to the east of it, ranging from 1000m all the way up to 6000m. I also put a sizable group of cargo ships in grid AR-11 to the west and also placed a "destroy ground" icon in the middle so I could see it on the map well before I could see the ships.
The distance gives you time to trim your plane (especially the rudder) and get it stable at altitude without any control inputs before kicking in "auto level". I also cut back on power and prop pitch...some planes not as much as others. Also, I found that as altitude increased, accuracy started to suffer, although not as much as you would expect. I'm still able to zero a freighter at 6000 meters alt with that big ole 5000 kilo monster the Pe-8 drops.
Anyway, if you want, get set up on that map and get used to running the numbers on your way to the target. Then, when you're ready for temperature changes, let me know. Additionally, I think a calculator will do you much better than your E6B due to the variations in the velocity factor. (.084, .066, .046, .026, etc)