The requirements the flight simulation places on your computer are very dependent on the game and the desired graphics quality. We cannot give a general recommendation for a suitable computer here. Please check the courses for the desired game to see whether the tutor makes recommendations or lists his own experiences with the required computer hardware in the documentation.
In the forums you can always find questions like this:
Yes, you need a joystick! The simulations we teach here are not action games like “World of Warplanes” and can therefore not be played sensibly with the mouse. But you don't have to spend several hundred Euros on joysticks and the like.
An inexpensive joystick for getting started is for example the T.Flight Hotas Stick X by Thrustmaster, which you can get at Amazon. Price / performance is excellent. For approximately €50 Euro you get a joystick, throttle control and the possibility to simulate the rudder by twisting the stick (Twist-Stick) or a big toggle switch at the throttle control. In addition there are 12 buttons to allocate.
However, unlike other joysticks, they cannot be freely programmed via software. You can only swap the buttons. If you want more, you should take a closer look at the software "AutoHotkey". I myself (kaltokri) flew with this joystick for 2 years.
Alternatives are e.g. the "T.Flight Stick X USB" or the "Speedlink Black Widow XE Flightstick". This HOTAS (Hands On Throttle And Stick) is just the thing for beginners who don't want to spend a lot.
Of course there are many more expensive HOTAS systems, all of which have different advantages and disadvantages. The tutors will be happy to share their own hardware experience with you.
If you have a joystick with a z-axis (e.g. a twist stick), this is sufficient for the beginning. If your joystick doesn't have a Z-axis, you have to control it with the keyboard, when taxiing for example. This makes things more difficult, but it is still feasible. My tip: Get a beginner HOTAS with Twist-Stick. With pedals you have even more feeling when controlling the plane, but at the beginning you might invest the money better in a head tracking system like TrackIR.
There are two known systems to transfer your head movement into the game. The older one is TrackIR. A tracker that looks like a webcam is placed on the monitor and a small arm with infrared LEDs is attached to the headset. For example, if you turn your head slightly to the left, the view in the virtual plane will change in the same direction, so you can see out of the left window. But you are still looking at your monitor.
As a video say louder than words, here is a link to an explanation from “FlightSim Junkie” on YouTube:
FreeTrack, OpenTrack and FaceTrackNoIr are free projects with instructions on how to build your own head tracker. I bought one for my son (DelanClip) that worked very well. But since Windows 10 the software FreeTrack wasn't running anymore. "OpenTrack" is a good alternative. The EDTracker is also a feasible and inexpensive solution but is limited to 3 degrees of freedom.
Here a very nice video how to build your own head tracker system:
VR (Virtual Reality) is slowly getting into gear. You put on a pair of glasses to replace the monitor. If you move your head, the movement is also transferred into the game and the image in the glasses adapts accordingly. Some of the flight simulations already support VR, but there are still weaknesses in the games.
VR systems are still very expensive and there are some people who feel mild nausea after 15-20 minutes. This is rather bad for simulations, as it may take 15 minutes to start an A-10C.
I myself have no VR yet and am very satisfied with my TrackIR. Without Head-Tracker I don't want to fly anymore. But it is not a requirement to participate in OFS courses.
Purchase a cheap entry-level HOTAS with a Z / Rotary axis.
Visit our taster courses to find out if flight simulations are something for you. If so, save for a TrackIR or build your own alternative system.
After some time you will be able to decide if you want a more expensive HOTAS and then you will be able to judge for yourself what makes sense for your needs.