how to keep clipboard always visible in writer?
how to see on my computer’s toolbar whether a clip has copied to my clipboard?
how to choose how a clip is pasted into a document (e.g. original formatting or destination formatting)?
how to choose defaults for the clipboard so never have to re-select them?
how to keep clipboard always visible in writer?
There’s no such feature in LibreOffice. Maybe you may use some OS/third party “clipboard manager” to do this (and I anticipate reasonable warnings from others regarding problems related to clipboard managers destroying clipboard in many inventive ways).
how to see on my computer’s toolbar whether a clip has copied to my clipboard?
Your computer’s toolbar is definitely not something that LibreOffice manages. See above.
how to choose how a clip is pasted into a document (e.g. original formatting or destination formatting)?
Use Edit|Paste Special (Ctrl+Shift+V).
how to choose defaults for the clipboard so never have to re-select them?
You can’t. It’s impossible; there are hundreds of clipboard formats that (a) possible to appear in clipboard (as the source application puts that to the clipboard), and (b) known to LibreOffice. Clipboard may have several of those formats at the same time - again, as source application had put there; and LibreOffice must decide which format is the best - not only from the random set of currently available formats, but also depending on context (was that LibreOffice’s own data in clipboard - for which it knows most? was the paste in “normal text”, or in a table - so that the best format could be chosen to put data to cells? Or maybe you have a selection - say, a graphical object?). There are unlimited combinations of the circumstances, and there may not be a single setting (or any manageable set of settings) to handle this.