financial dire straits and upkeep

[Ygramul]

How is the upkeep of a unit determined?
I know that supply depends on size.

Does a Shambler thrall [gold 35, res 1]
has more upkeep or a meteorite guard [g 10, r 30]?
How much?

Are the units the only source of deficit?
[If so this makes Province Defense a better
deal to a certain breaking point which
depends on the nation.]

While you are at it:
what are your finance strategies?
Order/Tax Rate/Patrol combinations? etc.

Thanks,

Ygramul