Flip over the Mac Mini so the open and closed dots are facing you. Twist the black base counter-clockwise to unlock the base, and gently lift the base clear of the device. Using the Torx T8 screwdriver bit, unscrew the screws for the wireless shroud. Gently start to remove the shroud until you see. Mac mini has some of the most versatile ports and connectivity options of any Mac, allowing it to serve and adapt to a wide variety of situations and workflows. Mac mini comes standard with 10/100/1000BASE-T Gigabit (1Gb) Ethernet using an RJ-45 connector. For network connections that are up to 10 times faster, Mac mini has a 10Gb Ethernet option. I can't really say what mac is the best mac but I can say that I have use 2009 mac mini with el capitan and it works just fine. If you were to get something a bit more up to date then you may be able to use features that are on Mojave? I would say from my experience, a mac mini with el capitan runs as it should but if you are able to afford. You can use any monitor with the new Mac mini 2018. (Except for an Apple one because they don’t make them any more!) The Mac mini has a HDMI port for a display, but you can also plug a monitor into any of the 4 USB-C ports. My strong advice it try to get a monitor that comes with a HDMI cable or a USB-C cable – don’t rely on Apple’s.
Learn more about using external displays. For example, you can use Displays preferences to arrange displays so that your iPad extends the left, right, top, or bottom of your desktop.
If you hover your pointer over the full-screen button of a window, you can choose to move that window to or from your iPad display. It's faster than dragging the window, and the window is perfectly resized for your display.
The sidebar puts commonly used controls on the side of your iPad screen. It includes Command, Shift, and other modifier keys, so you can choose essential commands with your finger or Apple Pencil instead of a keyboard.
Use Sidecar preferences to turn off the sidebar or change its position.
Tap to show or hide the menu bar when viewing a window in full screen on iPad.
Command. Touch and hold to set the Command key. Double-tap to lock the key.
Option. Touch and hold to set the Option key. Double-tap to lock the key.
Control. Touch and hold to set the Control key. Double-tap to lock the key.
Shift. Touch and hold to set the Shift key. Double-tap to lock the key.
Undo the last action. Some apps support multiple undos.
Many apps on Mac have Touch Bar controls that make common actions even easier. With Sidecar, you get a Touch Bar on your iPad screen even if your Mac doesn’t have a Touch Bar. It works just like the Touch Bar on Mac, and you can tap its controls with either your finger or Apple Pencil.
Use Sidecar preferences to turn off the Touch Bar or change its position.
If the Touch Bar doesn't appear when using an app that offers Touch Bar controls, choose Apple menu > System Preferences, click Mission Control, then make sure that “Displays have separate Spaces” is selected.
Multi-Touch gestures on iPad remain available when using Sidecar. These gestures are particularly useful with Sidecar:
To point, click, select, and perform tasks such as drawing, editing photos, and manipulating objects on your iPad while it's extending or mirroring your Mac display, you can use your Apple Pencil instead of the mouse or trackpad connected to your Mac. You can also use it to write, sketch, and mark up documents while seeing the updates live on your Mac.
Sidecar also supports double-tap, which you can turn on in Sidecar preferences. Double-tap enables apps that support this feature to perform custom actions when you double-tap on the side of your Apple Pencil (2nd generation).
During your Sidecar session, you can type using a keyboard connected to either your Mac or iPad, including the Smart Keyboard or Magic Keyboard for iPad.
To point, click, or select with a mouse or trackpad, use the mouse or trackpad connected to your Mac, or use an Apple Pencil on your iPad.
While using Sidecar, you can switch to an iPad app, then interact with that app on your iPad as you normally would. This suspends your Sidecar session until you switch back to the Sidecar app or disconnect Sidecar. The Sidecar app appears on your home screen only while using Sidecar.
Choose Apple menu > System Preferences, then click Sidecar. These preferences are available only on computers that support Sidecar.
Sidecar requires a compatible Mac using macOS Catalina and a compatible iPad using iPadOS 13: