I am one of the greatest Screenshot takers and editors in the Universe. So i am highly capable of answering these questions.
With that being said…
- While I do not use Cinnamon Desktop, if they are using the new Gnome Screenshot tool called Snapshot, this is a rework of the older gnome-screenshot tool. It does save to the clipboard, so pasting into an application like Inkscape is supported.
- Gnome Screenshots are saved in ~/Pictures/Screenshot and you cannot change this in the new application as it is hard coded in to the program. There are many contrived threads on this already.
- I personally use Inkscape to edit Screenshots. As is evidence here : Inkscapers & Pathmakers Welcome ! | The Inkscape WaterCooler ✍🏾 - #19 by hamrheadcorvette these are quick edits and easy to use for anyone. There’s also the fantastic tool like Flameshot, but it always breaks with every Gnome Update, so I revert to using Inkscape quick/easy.
- If you are using other applications outside of what is provided in Cinnamon, please reply below.