I'd love to make a video tutorial if I can ever get around to it. I will try to include a detailed written example of some turns in the next update.
The rooms are multiple tiles. A tile is about the size of the monster or loot icons, and the width of a narrow hallway. I draw the rooms with some variance. I usually play on grid paper, but sometimes to make the rooms fit I shorten or extend them. The biggest room is 3x5
The melee penalty is reduced by your skill with the weapon, not the weapon quality. So if your skill is at 3, then you have no penalty for attacking at melee range.
The way movement works is mostly relevant for when you have entered a room and monsters are moving towards you, since you will want to try and position yourself so that they can only come at you one at a time. It matters more with ranged weapons, since you can get the monster's attention, and if you have more movement than them, kind of kite them around and get more chance to attack, assuming you have enough clear space to maneuver in!
An example of a couple rounds would be something like this (very rough, please forgive me):
I reach a door to an open room and see there are 3 monsters inside...
Round 1:
Move: I step 1 tile into the room, alerting the monsters. There is a monster immediately to my left. If I don't move away or successfully attack it this turn, then it will hit me.
Attack: After finishing my movement, I can take 1 action - I attack the monster, defeating it.
Monster's turn: The monster in the top right of the room moves two spaces left and ends adjacent to me. If I don't move away or successfully attack it next turn, then it will hit me. The monster in the bottom right of the room moves three tiles left, and there is still one tile between it and me so I am safe.
Round 2:Move: Don't need to move since I want to hit these monsters anyway. If they were too high of a power level, I could use stealth or a spell to let me disengage and move away to a different room. For now I think I can take them.
Attack: Attack the monster adjacent to me, I miss, so that monster gets to attack me.
Monster's turn: The monster adjacent to me attacks, dealing damage. The second monster moves 1 tile up to be adjacent to me and will attack next turn.
Round 3:
Now I'm in trouble because even if I defeat a monster, I'm going to get hit at least once. Luckily I have 3 arcane skill and the shape stone spell.
Spell: I use the spell shape stone to make two walls (one down and to the right) between me and the monsters, and a door in the adjacent wall, opening a passage to another room where I hope to have better luck.