Hey Daniel,
you will appreciate the Triquetra 3-Axis Touch Probe, as it is a method of adding acceptable positioning repeatability to the machine. The stall homing method that the machine offers is considered by many users as not repeatable with sufficient precision and use a method with the Touch probe instead of it. It is however possible to retrofit inductive proximity sensors as limit switches, the Onefinity CNC supports it, but you would need some 3D-printed parts to attach them to the machine.
The Touch Display connected directly to the CNC Controller that Onefinity offers is rather small, okay for younger people who have no presbyopia yet 
and who have rather small fingers. Many people use much larger displays.
Note that many people dislike the magnet mount for this touch display because if you hit the display accidentally it can fall off and be broken. In the case you want to give this magnet display mount a try anyway and prevent to break it the first day when you hit it with your hips, don’t forget to secure it with a cable tie as shown here. Also the magnet itself can fall off on temperatures below 4.4 °C. UPDATE: The manufacturer doesn’t ship this magnet monitor mount anymore. You get a spring-loaded arm mount now.
Some people use other touch displays and stronger aftermarket display arms. For search criteria to find a touchscreen compatible with Onefinity and Buildbotics Controller see here;
But neither you need to connect a display directly to the Onefinity Controller nor is it mandatory to use a Touch Display. You can use a mouse and a keyboard instead and any old HDMI (or DVI-D or DVI-I which is compatible to HDMI) computer monitor connected to the Onefinity Controller. Using a Touch display on a CNC Router comes from the desire to have a display directly at the machine where there could be wood dust which normal keyboards and mice don’t like.
But you don’t need to attach a monitor to the controller directly at all. You can operate the CNC Controller from remote over Ethernet or WiFi from another computer and it has the advantage that you can see the CAMotics tool path simulation that is not shown on a display directly connected to the controller.
And of course you can have this other computer directly besides the CNC too
Powerful dust collection is mandatory since the ball screws are not sealed (industry machines have convoluted rubber gaiters or bellows covers to seal them) and oiled mechanics are generally incompatible with wood dust, as can be seen here, and also here:
For the difference between a workshop vacuum cleaner and a dust collection system, see here.
Most people like the ability to control the machine by hand. If you don’t like the gamepad aka joystick, then see here.
Note that in contrast to other CNC routers, the Onefinity CNC is a machine that comes without some essential parts: It lacks the milling motor which you have to buy separately and secondly the machine comes without machine base. It assumes that you either have a sturdy machine table with a table top of accurate coplanarity and that you are able to trim the machine for rectangularity (see here and here), or you have to buy the QCW Frame with it. In this case, don’t forget to order the Any Surface Leveling System with it! EDIT: The Any Surface Leveling System is now included with the QCW Frame.
If one day you find that your Z-axis moves up and down as it pleases and ruins your workpiece and your wasteboard, you might find that it’s because the connectors can make problems (see also here), which may be caused by the fact that you did not yet retrofit strain relief to your machine, which the machine unfortunately lacks. In this case you may want to procure what is needed to make new cables yourself. The same applies if you want custom length cables which would be the case if you want to mount the controller further away.
After having assembled the machine and pressed “home” for the first time, you may wonder if it’s correct that the Z assembly bumps the Y rail. In the case you don’t like it, you may want to know that Bill @Machinist found a simple solution here. This is also convenient on the Y axes in order to prevent that buildup of wooddust-oil mix gradually shifts your homing point backwards with time during stall homing.