The game has ruins all over the place. Huts, villages, towers, crypts, etc. Each biome has it's own kinds though, and meadow (where you start) mostly just has the little houses and villages. Those are likely what you are finding.

Branches are all over the ground for you to pick up but you do need to interact and actually pick them up. If you cant seem to find any of those you can also punch the smaller saplings or bushes down for some wood as well. once you have enough to make an axe, you can go for actual trees (though some trees might still be too hard for you).

You can, and many like to have at least a few places near water because sailing is a big part of this game so it can be a great idea to have a decent dock to repair your ships at and protect them when not in use. You wont have to immediately worry about it though and it is worth mentioning that coastal builds can have issues with tidal waves (though it doesnt actually hurt much, it can temporarily extinguish your fire, in which case you cant rest, cook, or use your bed while the fire is out).

Dead vikings do not require water, only mead! Though in all seriousness that is actually true. You dont need to hydrate in this game, but you will also find that later on in progression when you can make meads, meads are also sort of like your potions in this game, having special effects like resistances to certain hazards or buffs for the player.