Federally, if they passed directly to you, specifically in his will, then they are yours outright.
If they were not specifically listed in the will, then they belong to the beneficiary of his estate -- probably your mother.
If she wants them to be yours, and you live in the same state, she can transfer them to you in accordance with your state laws. (Probably nothing more than a simple gift, but could be more depending on your location.)
If they are legally hers, and you live in a DIFFERENT state, they would all have to be transferred to you through an FFL dealer (in YOUR state, in the case of handguns) -- or you could leave them in her ownership and let them pass to you in HER will (in which case they would not need to go through a dealer).
If any of them, as Unistat said, are NFA-regulated items (machine guns, silencers, short-barreled rifles or shotguns, destructive devices, or "AOWs") AND you are the DIRECT beneficiary, the executor of the estate may hold them while they are transferred to you, tax-exempt, on a "Form 5." (There is a sticky thread on this process in our NFA forum.)
There is no "armory license." (At least not in any state I know of...)
You do not need a C&R Collector's Type 03 Federal Firearms License, unless you want one. You do not need it to own and enjoy these. It can help you with further purchases.
Post pictures of anything you can't identify or you want more info on down in our "Firearms Research" forum and we'll give you more info than you even want!
Also, it would be worth having someone who really knows what they're doing look at a collection such as this before you ever consider selling any of it. There are some guns that are very similar to run-of-the-mill items but are actually worth a fortune. Especially as your father must have collected for decades, there is a strong likelihood that he collected more than a few items which have since become quite rare and valuable. Having them cataloged and appraised would be a wise move ... and consider an insurance rider to protect his investment.