Using melee weapons to injure enemies will get them to bleed, causing them to surrender easily.
Carts are useful to load injured, slow people inside of.
All additional people in your crew will consume food and water and may slow you down if they have low health or agility.
Escorting people, releasing prisoners, and release slaves to or in a town will create more unemployed people.
Unless trained extensively, it will do more harm than good to any sizeable caravan.
Keep in mind that hunting and foraging slow you down 5% each, thus increasing water/food/forage consumption on the road.
It might be best to get a rough estimate by looking only at your main food sources, ignoring sources from negligible amounts.)
(This is assuming your current ratio of food stock stays the same.
Your caravan will not eat extra food when out of water.
This final result is how much of your water need will be satisfied by food. Multiply that by the length of your trip in days. Multiply each number by the percent water content of the food, and add them together. Next to each food source is a number for how much is eaten per day.
To calculate how much water you are getting from your food: Go the "Supplies" tab in your Caravan Menu.
Forage can be looted from bandits that have animals.
Small but militant caravans can also hope to loot some water and food from dumb bandits on the way.
When running tight, you can skip about 5–10% of that (after accounting for foraging/hunting) if the road is not too long.
Always, always buy up water, food and forage for your next trip BEFORE stocking up.