For 1, I generally recommend whatever Doom is recommending[0], which is currently the tap you mentioned.
For 2, evil is indeed available by default in Doom and works normally with org-mode. For the most part, everything works just like in vim, including splitting panes (windows in emacs), switching tabs if you've enabled them, and so on. So, writing notes in org-mode should essentially be just like writing nodes in any other editor with vim keybindings. You've also got by default nice stuff corresponding to some of the popular vim plugins, including vim-surround and commenting (via `g c <motion>` or selecting a range and then `g c`). There was also this post I saw recently exploring `evil-snipe`, `evil-easymotion`, and a few other plugins available by default that was quite helpful[1]. There are also a number of useful org-mode specific functions available when you're editing an org file behind the "local leader" `spc m`, like ticking off checkboxes (`spc m x`), storing links (`spc m n`) inserting links (`spc m l`), toggling todos, setting priority, scheduling dates, and so on. `TAB` cycles folding of headlines, `shift+TAB` cycles headlines throughout the document.
In general, one of the nicest things about emacs is the ability to introspect everything at runtime. `spc h v` allows you to search for, check (and change) the value of any variable, and you can often do some exploration in the fuzzy finder to figure out what settings are available for whatever editor feature you're using. `spc h k` lets you type a keybinding and gives you the documentation for whatever function it's mapped to. `spc :` or `M-x` opens up a fuzzy finder for all the functions available in the editor. You can search through these to find stuff you might like to do, and see inline which keybinding the function is bound to, if any. `spc h a` searches all functions, variables, etc., in a similar way. `spc h i` opens up an info browser, which is like man pages on steroids. Many emacs plugins have documentation here, as well as many system utilities. Last but not least, the help for Doom itself is quite nice, which you can get to via `spc h d m` (help for doom modules), `spc h d h` (general doom help), and so on.
For org-mode, you can learn a lot of what's available by typing `spc :` and then just reading through all the functions that start with `org-`.
[0]: https://github.com/hlissner/doom-emacs/blob/develop/docs/get...
[1]: https://medium.com/@aria_39488/the-niceties-of-evil-in-doom-...