You're aware that client Wi-Fi adapters are a no go to use in a router, right? What you're doing with your RPi and some trinkets aren't going to translate well if you're going to try to build your own router.
What you'd need to get is something like this, but I'm not sure if there are drivers for a DIY build for it.
The QWA-AC2600 is a 2.4/5 GHz Dual Band Dual Concurrent (DBDC), 4 x 4 Multi-user MIMO (MU-MIMO), low-profile PCI Express (PCIe) 2.0 x1 wireless adapter with two Qualcomm QCA9984 NICs that supports up to 2533 Mbps (800 Mbps for IEEE 802.11n (2.4 GHz) and 1733 Mbps for IEEE 802.11ac (5 GHz)). The...
www.qnap.com
A client Wi-Fi adapter, such as the ones from Intel, will crap out after you connect a handful of devices to it, if even that. They weren't designed for routing traffic from multiple devices.
I used to work for a router manufacturer, so I'm well aware of not just driver issues, but also the amount of tuning that can be done to make the drivers work well for specific hardware combinations. The big problem with anything Wi-Fi is that there just aren't any good open drivers and the binary blobs from the hardware vendors tend to have their fair share of bugs, that sometimes never gets fixed. We ran into an issue with a Wi-Fi chip from MTK and it took them three months just to acknowledge there was an issue and another couple of months to fix it. If that's how it is to be a paying customer, it's no wonder that so many retail products work as well as they do. The router hardware vendors really need to step up their game, but alas, it seems like that's not going to happen until they get slapped hard by some court.