1) Tools > Options > Codetools: "Jump directly to message body".
This should change what jump to implementation does. I never used it, but afaik that is how it works
going back: alt-h (not sure maybe ctrl-h) in either case you can assign it to other keys, maybe ALT- cursor-left
2)
Lazarus doesn't pop up. But "Find references" gives you this list, in a separate window
It works for any identifier, functions , variables, classes....
Alt-h should work after jumping to any of them
4) And "Lock" it.
this will mean if you navigate around in the unit (search results, jump to other declaration/implementation....) then it will use the unlocked window.
There are some options in the Tools>Option > Editor > Pages and Windows
that determine which window to use as target.