The tp-link CR1900 is meant to act as both your cable modem and DHCP/firewall/router/WAP combo. Is this what is provided by your ISP? If not and you have the choice to use another modem, since you want to use pfsense you would be better off choosing a cable modem without firewall/wireless. Otherwise you would need to disable those features (bridge mode) in order to avoid double NAT when adding a pfsense firewall/router. Technically it is possible to run pfsense behind a NAT’d modem, but it is a huge PITA (ie you don’t want to do it).
Since you plan on running unRAID, you could install pfsense on unRAID to play around with it. That is exactly what I did when starting out with pfsense. But keep in mind it can be tricky. It requires better planning, as you could find yourself in a catch 22 situation, because your network connectivity is dependent upon pfsense but since your server is running it, if you stop the unRAID array for any reason your network is disabled, because docker and VM cannot run while the array is disabled. And there are many reasons to stop the array, including changing network settings in unRAID, for example. So, this is why most users will discourage running pfsense on unRAID.
As for wireless, there is a wireless TAB in Interface - Assignments in pfsense to manage wireless devices in pfsense, it is often recommended not to use it for reasons previously mentioned in this thread. It is generally advised to put the wireless access point(s) you use in bridge mode and assign them a static ip in pfsense. This ensures no DHCP conflicts (double NAT) between pfsense and WAP within your local network and also ensures that your WAP’s are always assigned an IP address in pfsense. Using this method the WAP handles the wireless connectivity, including wireless passwords, but pfsnese handles DHCP/firewall.
As others have said, buy an HP 290 for about $100, and use it as a standalone pfsense box. It will be less hassle. Pick up a WAP, such as Unifi AP Lite.