If you are using an external keyboard and a mouse with it - you will get the same touch UI, yes.
This is true. To see the ones that are available, hold down the command ⌘ key to get a scrollable list of all of the shortcuts for the app you’re currently using, and use Fn-m or globe key-m to see a list of the system shortcuts.
Very vague specs.
Can iPad Air USB-C deliver 4k 120hz or how much bandwidth that USB-C got?
I used to code HTML/CSS that way back in... 2011?