An overview of the brands and my take on some of them are here: drawing tablet brands
Read : using an iPad as a drawing tablet
It is possible in some cases. More here: Using a drawing tablet with an iOS device
YES, It is possible, but be prepared for potential limitations. Read more here: Using a a drawing tablet with a Chromebook
It really depends on a lot of factors.
For pen tablets - I recommend a MEDIUM size (about 11")
For pen displays - I recommend a MEDIUM size (about 16") though many start off with a 13" and I personally prefer a 22"
More here: tablet size
Answer: Yes, but ONLY if the manufacturer recommends it. More here: firmware.
There is no single right answer. Each has pros and cons. More here: Pen tablets vs pen displays
To avoid the light sources from interfering with using your drawing tablet, Manufacturers apply an anti-glare treatment to drawing tablets. This anti-glare treatment disperses like from the tablet in such a way that you see it as a colorful sparkle. Read more here: anti-glare sparkle.
Answer: YES. But there are some things you should consider if you want to use it this way: Using a pen display as a monitor
This is temporary phenomena called Image Persistence. This is not a permanent change and is not screen burn in (https://en.wikipedia.org/wiki/Screen_burn-in).
Answer: YES. More here: Using a pen display as a pen tablet
See this: Mirroring or extending your desktop to a pen display
The drivers that manufacturers release for their drawing tablets support Mouse Mode often only on their pen tablets but not on pen displays.
It MAY be possible to fix. More here: Dead pixels.
Answer: YES. All drawing tablets experience some kind of lag. Pen tablets experience less lag than pen displays. However, extreme lag is not normal. You should be able to comfortably draw even if there is some lag. Read my notes on pen lag
Yes. More here: Extending cables
There are quite a few. See this list: Subreddits for drawing tablets.
See: Protective sheets
See this guide: Dealing with water damage
Answer: I personally do not recommend this,. However. YES it is possible, but BE CAREFUL and DO YOUR RESEARCH. There are potential risks to your pen and tablet. More here: Using Metal Nibs
More here: Connecting a pen to a drawing tablet
You just need to buy a pen of the SAME EXACT MODEL and it will work with your tablet. You don't even have to connect it - just bring it close to your tablet and it will work.
See: Troubleshoot driver no longer supports a drawing tablet
It depends. More here: Using multiple tablets on the same computer