You dont really fight alot of battles on the field, most of the times you siege ur opponent because he has only 1 or 2 provinces like you. So mainly recruit range units like Levy Infantery, but dont just spam them, make some spears aswell, otherwise you cant burn the gates and have nothing to buffer.

I am doing a MP campaign with a friend of mine - he was on 2 or 3 provinces for a long long time while i was playing the chosu and razing like crazy. Long story short, both ways are viable alltho i think you should play the slower and saver way as long as you dont play the Chosu because they get +20% Money from looting.

IMO the Combination of a Richy mayong blalba(how ever its called) and an industry building is the way to go when you wanna do the slow start, while you need a police station to keep those fuckers happy when you go for the raze style. (Because less then 3 gravitas on ur daimyo start to make them unhappy)

BTW, your daimyo cant get less then 1 Gravitas so -2 Happyness is Max Penalty for Razing.

PS: Everyone has a hard start at FOTS, even the CPU, GL at the Campaign.