While all of the manufacturing that I'm looking to do initially is fairly basic (if I go though with getting a Type 07 FFL like I plan to), I'd potentially like to try more advanced things in the future. Does all of the manufacturing need to take place at the Business/Activity Address listed on the FFL and does all of the machinery need to be owned by the business/FFL holder? The reason I ask is because while I own basic tools, I do have some friends that own various pieces of machining equipment. I've been looking for different information about it for a few days now but haven't been able to find a concrete answer regarding if anything related to the manufacturing could be done at a different location. I also have a relationship with the owner of a machine shop so the idea of either using/borrowing equipment from friends or potentially renting the machine shop as opposed to having to buy a machine that may not end up being used much or useful would be really amazing. Thanks for all of your help and information!

Actions, receivers, and frames (the serialized part) must be manufactured at an address on the license. You can outsource fabrication of these parts to another company if they hold a class 7 or 10 FFL, but there are rules on how you go about doing this. For example, some of us have agreements with other manufactures to fabricate lowers and/or actions for us with our branding and serial numbers on their parts. In these arrangements a variance is filed with the ATF and must be approved.

There are certain stages of production were the components are not considered firearms yet. If you were EDM'ing a feature before the trigger pocket it cut at a friends shop, and then completing the part in-house this might be OK. It all depends on what state the component is when it leaves the other facility. 80% lowers are probably the most common retail example of this, but the same regulations apply to a manufacturer that govern when it's considered a firearm by the ATF. I personally wouldn't do this unless it was crystal clear that the part was not considered a firearm when it left the other facility. You get into gray areas quickly the closer to completion the part is but you will have to research that and decide for yourself.

Any other components of a firearm can be manufactured where ever you want. I prototype parts and test G-Code for production runs on various components at my home shop all the time, but I only produce serialized designs at the address on the FFL to make sure there is never any misunderstanding.

Nothing is required to be "manufactured" at the premises. You can literally buy all the parts to make a gun from Brownells, and then only do final assembly at your premises. However, if you are going to "manufacture" regulated parts, that must be done at your premises or you need a variance as stated above. You also are not required to own tooling, you can lease machines, buildings, etc.