First - you don't need a router or an access point to have a network or use a NAS - the purpose of the router is to allow your network to connect to another network, usually the internet, and the purpose of a wireless access point is to allow a wired network to be extended wirelessly.
Second - there's no reason why the NAS should not be physically located in an inaccessible location, as long as you have a network connection to it, you can access the files on it.
To answer your question - yes - a laptop can be used as a router, provided that it has multiple network interfaces - a router is nothing more than a special purpose computer with multiple network interfaces - having said that, whilst it can be done, it doesn't mean it should be done, and since you have to ask, you're going to need to call in someone to do it for you, buying a router would probably be cheaper.