Welcome.
edit: Djaydino beat me to it
1) Yes.
2) Yes.
You can peruse and search the actions in the action browser to get an idea what kind of stuff exists. They usually cover the most common cases. Next, PlayMaker has a few addons (for free), of which
Ecosystem is the most important. It allows to easily search and download additional actions for more specific purposes. Lastly, you can find tons of actions through this forum, and if you still miss something, there’s sub-forum where you can ask nicely if someone writes or adapts the action you need.
For arrays, there are also add-ons like
ArrayMaker, too (but first check regular actions).
PlayMaker uses regular c# scripts with some wrap, and as such, it is compatible with everything else that can be controlled with scripts. As I wrote above, popular assets might be covered already, and you can ask for actions.
There are also actions like Get Property and Set Property that can more generally communicate with scripts. Try to drag and drop a script into the action area.
Last but not least, you can write your own custom actions (see my sig). Stuff like setting variables or reading them is not that difficult but super worth starting with. It’s also a good gateway to scripting yourself (PlayMaker stays useful even if you can code).