Make sure to keep the Order at 95+, low Order will decrease number of troops recruited, gold and food income
For Researching... it's up to you but I think most players will first get the extra 20 Will..
And if u feel there's too much food and u seem to be short on Gold, sell some of those...
Also, keep enough officers on ur 'main base'...

Hmm, I believe that there's some occasion of which u can eventually exploit it's weakness (hint : Goodwill and Alliance)

Emm, if you we're asking what would I build first, it'd be the Farm and Market... Barracks and Smith/Stable comes second, then Workshop/Port (?) comes last .... and yes, Granary and Mint is necessary since it increases your Gold/Food income by 0.5,

for example let's say u have 3 markets with no Mint, u gain 150 Gold per month, build a mint in the middle of the 3 markets and it'll become 225 Gold per month, same works on Farms, but building several of those won't increase more. (Only 1 needed)

oh and be sure to limit how much farms/markets u want to build, especially in cities which have few empty lands such as Jiang Xia, Xiao Pei, and others that is....

Well it depends, I usually send like 2 Spear generals, 1 or 2 pike general, 2 bow generals and 1 Cavalry, to balance out things..... but if u like, u can just send out a whole army of 'S-Cavalry' for the entire game

That only affects the maximum number of soldiers u can march, and only give ranks to officers which u frequently use to attack.... rewards are a must, since some officers can betray you even if their Loyalty drops below 95 so reward them when u can, giving items are optional....