1. Conceptual Balance makes a good job in balancing the game. It's used in many multiplayer games.
Other mods haven't been discussed much. They appear, and then exist but are often forgotten. I'd recommend my Ulm Graphics Improvement - it makes Ulmish shields look a bit better, and does nothing else. Personally, I like it.
3. I'm not so sure about item combos. It's the effects, not the items, I'm interested in. As an example, one could get Quickness and some protection with very different ways, e.g. Boots of Quickness and Weightless Chain Mail, Jade Armor and Girdle of Might (helps a little against the increased encumberance of the Jade Armor), etc.
Usually, you want your mages to have booster items (Earth Boots, Crystal Coin) or reinvigorating items (Boots of the Messenger, Girdle of Might, Amulet of Resilience), possibly protective items (Boots of Stone, Weightless Chain Mail, light shield and/or missile protection), and items which increase their abilities for combat (Boots of Quickness/Jade Armor, Eye of Aiming).
Human melee commanders aren't usually worth giving items. They can use things like Sceptre of Authority and Skull Talisman, though. The commanders who are tough enough to survive in battle are different, and sometimes worth giving items. Jotun Herses are a good example. Also, lots of summonable units are good. The important things with Thugs or more powerful Super Combatants is to keep them alive (high prot, def, regeneration and/or life draining, luck, etherealness, lots of magic resistance, as many resistances/immunities as possible) and causing damage (multiple attacks, Quickness, Fire/Astral Shield, Breath of Winter or e.g. Rime Hauberk), with as low encumberanace as possible and with reinvigoration if Encumberance isn't 0. If enc is 0, the unit will only get fatique from spells and spellcasting.
Wraith Sword is very powerful with Conceptual Balance Mods, Starshine Skullcap gives magic resistance to anyone, high-def weapons like Sword of Quickness are generally good.
4. Supply items affect the whole province. If the same commander has two same items, only one has any effect. Because of this, it usually is worth it spreading the items out to many units. However, Scouts are usually preferred, as they don't die as often.
Remember that Endless Vineskin is the most economical choice, and that Summer Sword also exists.
5. I sometimes do that, but they would have to be quite powerful to be worth the gems. Jotun Herses can be like that. Sometimes I recruit cavalry commanders and give them bodyguards (units with Guard Commander order) and try to use his slightly better combat commands to target the enemy commanders or mages.
With Ulm, Black Lords can be powerful, but are still weak against magic. While testing with Conceptual Balance, I found that the national heroes have much more potential as combatants.
Usually it's better to give them ranged weapons. Commanders can Fire Rear.
6. I usually script my mages. Usually it's quite simple, like Body Ethereal, Eagle Eyes, Nether Darts for my Seithkona. I don't script all of their five spells every time.
If you hover your mouse above a commander's orders and press Ctrl+number (0-9), that set of orders is saved. You can give the same orders for any other commander by hovering the mouse above his/her commands, and then pressing the number you saved the set of commands in.
Couple of questions
Linear Mode
