Do gnomes kill other gnomes? If so, how

On the highest level menu there is a big X button as the last option. It is the "Cancel Job" Button. Use this to cancel any commands you make.

Your strategy of a wall around your camp and having a training yard assigned to your guards at the entrance is a good start, but here's some other things you can do to survive the first summer:

• Enemy difficulty scales with your kingdom worth, so try and keep it low until you've geared your defense squad. I'd recommend staying around 2-3k if possible.

  At around 5k kingdom worth, you start getting goblin fighters who can be geared in copper weapons and armor, and are much more damaging to your tiny gnome village than regular unarmed goblins.

• Put all your worker gnomes into other non-attacking squads, and set them to Respond to Attack Orders. Then when a goblin shows up, use the Attack button to have your entire camp jump on them. This kills them much faster, and minimizes the damage they end up doing.

  I actually had all my workers responding to attack orders for quite a while (I think 20k kingdom wealth?), until I had my guards geared and found my unarmed gnomes were dying before my guards got there.

• Keep bandages in stock, ideally at the entrance to your camp. Gnomes will heal themselves with a bandage if they can, and immediately return to their duties at full health. If they can't heal themselves (no bandages or no arms), they'll sit around in the hospital and wait for a doctor to come heal them, which takes forever.

  I don't think the hospital zone provides any kind of healing capabilities on its own... I know I've had gnomes die from bleeding out in the hospital. They seem like just a place for injured gnomes to gather when they're wounded, or to get fed if they can't feed themselves. The zone also need beds to function.

• Try to get a Market Stall built by Day 5. If you have one, a merchant will appear at sunrise and you can buy many items that could help your early game depending on what you need. Copper, Cotton (for bandages), Animals, Seeds, etc.

  To make money to buy his items, I usually recommend Stone or Clay statues since they can be made of fairly common materials early on, are relatively quick to craft, and sell OK.