Resupplying Units

I'm currently making a return after about 3 years now since I last played. After having steam-rolled a few C3s and relearning the war aspect of the game, I am still unaware if there is a feature that allows units that have suffered losses to be resupplied off of the world market automatically, including ammunition to bring up default levels - or if I need to manually purchase the units and ammo (at least, the ammunition that would be separate from a small stockpile built up due to the trade strategies, seeing as how that would be in a much larger quantity).

Thanks

As well as this, I was curious to know if I were to deploy garrisons, whether purchase orders would be created automatically to acquire all weapons and ammo, or if I would need to purchase all supplies pertinent to mobilizing defensive forces manually?

You will want to manually create purchase orders because you can request 330Q. If you create auto-ordering per month to build a stockpile, it is limited to 300. Auto orders because you are out of something can vary considerably in Q.

As a general rule, it is better to have the weapons stockpiles for your defense (ie garrisons) in your enterprise ready to mobilize in case of war. Maintaining truly fortified garrisons is expensive.

Thanks for the response - although my question was primarily directed at whether the game had a specific function to order off of the world market to resupply units in the case that sufficient stockpiles are not present, and that these automatic orders are not the result of the trade strategies at the same time. Sorry for the confusion.

Your country buys the supplies it needs and that includes military. Typically, I think it is set at 4 months/9months. So when your country supply goes below 4 months, it will order 9 months of supplies. This would include the ammo needed for the country. It won't order the units though because those are not used on a monthly basis. There is not a separate function to order supplies for the military.
Again, you don't want the country to order the ammo. You should manually order it so it will be a higher quality.