I know most of the research rules for world standard and below but I don't have the definitive formulas for world standard + 1 and for H. Bomber Evasion and Land Attack.
For world standard and below, listed research cost is 5 + (# of units)/5 with all fractions rounded up. * Note that # of units includes built units you control, frozen units, units in the build queue, and units on hold in the build queue with equal weight.
If your researched value is 0, you can spend 1, if it is 1, you can spend 2, if it is 2+, you can spend 3.
There is a chance that when your research cost falls on a fraction, it could be the lower number.
This chance is equal to 100% - fractional%. So 2/5 = 40% => 100% - 40% = 60% chance of rounding down.
You can spend up to 1 more than listed cost of your technology, which this extra 1 carrying over (2 carry over if you also have a rounding down).
The benefit of a carry over is that you start ahead on the research spending scale (can spend 2 instead of 1, since value is 1 instead of 0 for instance).
With all that, my questions are:
What is the formula for listed research cost for world standard + x?
What are the spending maximums by current value at world standard + 1, 2, 3?
What is the spending maximum pattern for H. Bomber Evasion and Land Attack?
Do attribute values over 10 actually mean anything?