I agree playing gnome is difficult, I would say for advanced users or people looking for a challenge. It was easier/funner to play a Dwarf. Actually, I think in scales of easy/fun it goes: Human, Orc, Dwarf, Elf, Gnome. Well, I had more fun as Elf than Dwarf, but Dwarf was much easier.
I didn't run into any issues with armory as a gnome. I just kept it running all the time - even night. Also, I found if you make the big investment in mills (running 2 to 2.5 per land) it's easier to keep up with constant cat production, and since they don't take up much room once built - you can save on GH to use on more mills or houses.
The extra space on GH is a definite help too, it's practically like a pop bonus. Also the fact that cat/bal only take 1 slot in GH is nice, since they take 4/5 men to produce and pack a huge power - I keep ATC training non-stop.
For gnomes, I think it's important they live in Alderd to get racial bonuses, they really need it. Also, having Blessing on 24/7 via magic potion is also necessary.
Lost my army a few times now. It's really slow going to rebuild ATC. I haven't figured out a good strategy for that yet - mostly because I've only been bottom fed by suiciders in the top-10. I think the new rules for anti BF may help, someone my own size would probably not fair too well against my ATC heavy gnome, and I've been adding tech to increase ATC units attack.
How I foresee an ideal war strat: I would send first wave as ATC heavy. Then, supplement losses with TC units that build fast. Repeat with TC until the war is over... During a "rebuild week" I would dump the TC and max out ATC production. IMO the TC units are useless to keep on hand for anything, only really useful during an active war with someone to quickly replenish troop supply. Keeping stockpile healthy is important for that.
I also didn't make a single Rider. It's expensive and adds extra complexity to my strategy without much benefit. I run out of resource before I can make more cat/bal/infantry each tick, not worth trying to sacrifice other more useful units for some poney guys. The Rider seems to have been originally built just as a placeholder because "all races get an animal unit", doesn't really seem to fit in for gnomes. I'd rather have it be another ranged or dual range/melee unit like the humans mounted archer.