The first hero. Army or city?

[Qwertion]

What is more beneficial to assign him to? What do you prefer? What are the benefits of each? (I suppose it gives city some bonuses, but don't know which)

[SylverMelody]

I usually re-assign my hero to the city at the start unless it has no FIDS boosting skill attached to it. The exact benefits this provides depends entirely on the particular hero and what skills they have, and may not provide any at all if the FIDS skills aren't present.

[Strandly]

Depends on the hero. Some have (or had, maybe it changed) battle friendly innate abilities and others had abilities that buffed cities. I don't remember ever getting a city friendly hero at then start, I always had to buy them in the marketplace.

[Qwertion]

I see. To avoid making more useless noob topics - can enemies assimilate villages I peacefully pacify in not controlled by me regions?

[Ninthshadow]

A vast majority of games, I would say army is the better choice.

The XP bonus from Ruins, dealing with minor factions and finally miscellanous scuffles is too good to pass up. For some factions, the hero is all that keeps the early armies alive.

Although the starting heroes typically have a little bit of everything to keep their options open, their governer traits alone typically aren't awesome for extreme early game.

Even the factions with great city skills will need some XP to get them started, which is based on buildings produced and units in the garrison, neither of which you have too much of at the start of the game.

Building production maybe okay but if we're crunching numbers, I can't see it compete with "X just for searching this ruin", "Y just for looking into a parley quest" on top of whatever else you do.

By the time it makes sense to grab a governor, you probably have the market where you can find someone more specialised for it than your first hero, who's probably still busy exploring ruins or pacifying villages.

Quick edit for question 2:

Yes, is the short answer. If you pacified a village in enemy territory, they'd get the benefits of it. So recklessly clearing out all nearby regions may not be the best strategy. If the enemy colonises before you do, they reap the long-term rewards.

I typically try to pacify a region at about the same time I settle it. That way, I know I'm not just making an AI's life easier.

[foetus sub mundi]

Most games, you're going to want at least one of each, general and governor. The first one depends on what your starting hero is doing, which is largely about what faction you are. Cultist? Your starting hero is as good of a governor as there will ever be, and there's no need for you to ever get a second. Broken Lords, Drakken? Your starting hero makes a fantastic general but a subpar governor. Get a governor.