List of keys and mapped actions? & how to configure? Where should custom highlight setting be?

[twisteria]

I think this is very basic things, but could not find any source explaining these somehow...

Where can I find documents for default keybinding included in ```cmp.mapping.preset.cmdline(),

Also, how can I change/add new binding(s)? ```cmp.mapping.preset.cmdline.insert({ .... })``` does not seem to be working..

One more thing.
I've been trying to set below, to disable highlighting of matched letter(s),
```highlight! link CmpItemAbbrMatch Pmenu
highlight! link CmpItemAbbrMatchFuzzy Pmenu```
but cannot make them work(```:hi``` indicates those groups are mapped somewhere else).
Where those settings supposed to be fit?