Three most important strategy elements at start:

[Gedrin]

Well I certainly do not play with CTP out of the box. I have a number of triggers and changes that really change a lot.

However, I find Slavers and Growth were the best long term solutions. Granted I would get behind in tech but that was easily, WAY TOO easily solved with the P. Stone. This whole drive for war walker? Even on diety my games don't get to war-walkers... everyone was dead by then. I often got to but rarely got past the tank. Of course with all the mods I play with now it is much harder.

Oh and BirdMan. I think you overlooked an effect.
Granaries to not produce more food. The flag for granaries is:
IMPROVEMENT_FLAG_SILO 50
Which means it consumes only 50% of stored food when your city grows. I think there have been misleading manuals out there that tell you they produce more food but as you stated they do not. They also give you the time to fix the fact that this new pop cannot produce enough food to feed itself... and build a farm.

If you want more food the the aquaduct has flag:
IMPROVEMENT_FLAG_PRODUCTION_PERCENT PRODUCTION_TYPE_FOOD 20
Which gives 20% more food.

[Solver]

Yes, why the War Walker is considered the most powerful unit in the game so often?They're good, but not the brst. It has a nice capability of ranged attack, for sure, but it has a normal attack of 12, what equals to a standard and cheap Marine.
War Walkers are very fast and they can bombard, so I surely like them. But they do better when mixed with other types of units, like Tanks.
War Walkers aren't that way easy to counter. You need another bombard unit for that, that's the best choice.
Oh, and if you can wipe out everyone on deity before War Walkers, you might just be called an expert.
I like keeping one civ alive to continue the game, get the technologies and then either:
A.Wipe them out with superb technologies - let my Swarms and Space Marines fight their Musketeers.
B. Do the same as in A, but leave one of their cities. Then build an Alien at my Xenoform Labor. This way I won't have the conquest victory.

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Solver - http://www.aok.20m.com