This app was mentioned in 6 comments, with an average of 1.33 upvotes
MRU Widget on the play store: https://play.google.com/store/apps/details?id=day.cloudy.apps.mru
\1. You can use Google Keep on a browser or Microsoft OneNote app that is probably installed on your PC. Google Keep has an app for Android you can find by searching in Play Store. OneNote also has an app on play store and if your Samsung Notes app is updated (or can be updated) to a recent version it can sync notes with OneNote as well.
\2. You can add the icon of the app to home screen to quickly / easily open it. To do that go back to home screen, open the app drawer (it might have a button with 9 dots or you might need to swipe upwards), find the app you want, touch and hold (wait until you can move it by dragging), then move it downwards to get to home screen, place it in a suitable location. You can also set it as a lock screen shortcut instead of phone or camera. (Ask if you want how) There are ways to make it automatically launch/launch when you tap the wallpaper, but I wouldn't recommend doing that as it is too much work for something that might not be very helpful. The app will stay open as long as you don't exit it, so the best way to achieve what you want is to never exit the app I guess.
\9. The recents menu shows you which apps are open. Different devices have different ways to open recents. If you have 3 software buttons at the bottom, you need to touch the square-ish button to the left side. It might look like 3 vertical lines next to each other or two L shapes. If you have a hardware button at the bottom, there must be two capacitive buttons to the left and right of it. Once again try the left one. If there are no buttons, you're probably using gesture navigation. Swipe up from very bottom and then keep holding/move your finger a little bit rightwards to open recents. For tabs, open your browser and touch the square icon with a number inside it. It might also have a smiley face if you have many tabs. Go to Settings>Display>Navigation Bar to change the navigation style. Also worth mentioning that the back button on bottom right (or swipe from edge gesture) works in most apps to go to the previous page. If there is no previous page, it closes the apps and exits them. If you want to exit an app without closing it use the home button in the middle or swipe up for gesture navigation.
\3. If you're on Android 9 or higher recents show suggested apps, but the suggestions might not be very helpful. I did a search in google play store and this app came up. It looks abandoned and reviews say it doesn't work (especially on newer android versions) but you can try that too. Custom launchers (custom home screens) usually offer suggested apps as well. Fan favorites are Customised Pixel Launcher and Nova Luncher. If what you want is stats, on Android 9 and higher, you can check the digital wellbeing menu from settings to see stats of how much you've used your tablet.
\4. Tablets are supposed to be portable. If you are in front of your computer while using it, I suggest you just use the computer for the most part. If you want to use an Android app that's not available on windows in the computer's screen, you can use Microsoft's Your Phone app. It lets you mirror your tablet's screen to your computer. First open settings in Windows, click phone and add a phone. Choose Android. Newer Samsung devices have the companion app baked in (with the name "link to windows") while on others you need to search play store for "Your Phone Companion". To see if yours has it open quick settings (the page you swipe down with buttons for toggling wifi, Bluetooth and such. Look for a button called "Link to Windows". Follow the setup to pair your devices. Once it is done, you can open the Apps tab I the windows program and click "Open phone screen" to start casting the screen of your tablet to your computer. Alternatively, some Samsung devices also offer a feature called Samsung Dex, I can explain that too if you want (check for a quick settings tile to see if you have it)
\5. Settings>Display>Screen Zoom. If you're not satisfied you can open developer options and set the screen width to something wider. (Settings>Info>Software Information> touch build number 7 times, the go to Settings>Developer Options scroll down to minimum width and set it to something a little higher. Be sure to not touch anything else or enter a number too big.). Custom launchers generally give options to adjust icons in their settings as well.
\6. I suggest trying out icons for a bit as different shapes/ colors generally make recognizing different applications easier. If you insist, you can try out one of these launchers: Neue or Aero.
\7. No. And don't install any app that claims to do so. Don't install apps that clean viruses, claim to make your device faster, increase battery life or such. Visit Settings>Device care and touch optimize every once in a while and you're done.
\10. Settings>Apps lists all installed apps. Alternatively you can find the app in home credentials, press and hold it then touch uninstall or disable.
\11. There are tons of 3rd party apps that replace stock apps such as dialer, gallery and so on on Play Store and a few are windows themed. You can install & use those but I think most such apps have poor user experience in general. The stock ui isn't so bad when you use it for a while.
\12. To set an image as wallpaper you can open gallery>touch 3 dots> set as wallpaper. You can search Google and download wallpapers that way or install a wallpaper app from play store to obtain wallpapers. Alternatively you can go to open Samsung Themes (or go toSettings>Themes) go to wallpapers section and choose from there as well. You can set from your device by tapping my wallpapers then gallery. Or, you should be able to press and hold/ pinch to reveal a wallpapers button in the home screen.
Tried this when it first came out and it worked well. I'm fairly certain there are others though the names escape me.
https://play.google.com/store/apps/details?id=day.cloudy.apps.mru