I made it as far as fifth island so far, and I never found a way to directly tell your villagers what to do. You have to learn how they react to your actions and then avoid doing things that cause them to behave badly. I find engineers are particularly badly behaved. When you start building forward wall and have catapult at the previous wall, they give priority to pushing the catapult slowly to it's next destination and THEN build the wall. And then it's evening and you still have only level 1 wall (in the better case) to hold the enemies. Solved by having surplus engineers and starting early in the morning, that way you can usually max the new wall by the evening. Unless they think it's better idea to go cut trees you have marked - so don't do that either.

AFAICT, archers always do one-left-one-right when recruited and gather near the outer wall of that side of the town. And no way to redistribute them. If one side gets seriously weakened in an attack, that's as good as a loss. If you manage to stop the wave and have lots of gold saved you can try to re-recruit the people and give them new bows, but you have to move very fast to pull if off. There is usually one day without monsters after heavy wave (blood moon). I'm dangerously near such situation on the fifth island, but I have ship built and waiting for me, so if things start looking dire I have an escape route.

And don't bother with towers too much, they are weak without walls before them to hold off the monsters. There are max 3 archers in each and the monsters move past them too fast for them to do any significant damage. Only thing positive about tower is that normal monster can't reach your archers - but flying horrors can. Only way to survive later in the game is a wall, strong garrison of archers behind it and a catapult. Even knights don't do much good in defense, they are for attacking.

By the way 4th and 5th islands have no travelling merchant, you have to survive only on farms and hunting. Good luck,

Take a look here for a good info let's play from this game.

https://www.youtube.com/playlist?list=PLGe_S5n7MjT32kTygnL_hPkbXZ8CEQ5bH

Hmmm the game and soundtrack is on a deep discount (85%) however the royal edition only 40% despite the only difference being the included soundtrack right?. The game worth a go? replayability? (not finding many of the deep discounted games that i dont have, appealing to me...many of the ones i dont have seemingly have poor reviews..)

Kingdom:Classic is free to play on steam so you might want to demo it, New lands brings new stuff but the formula is basically the same. It has a slow pace but for me it's addictive.

Yes. It'd badly balanced compared to the original (it has trap options and it's harder, so you're punished for trying different things) but still worth it.
Like looking at a beautiful painting - you might want to look at it again.