By the way, I forgot to say welcome to the Hubitat forums!
Yep, you want to save that for edge-use cases or complex automations. It is a very powerful app, but with that it is harder to use.
I suppose that depends... but generally you can do things in one "rule".
Some apps it is easy to keep things within one rule and others it might be easier to use separate rules. It may also depend upon how complex you are trying to be, whether you are using motion sensors, contact sensors, switches, or whatever.
And it also might depend upon if you want the same triggering device for both events, or whether you want to say use the Kitchen light to turn something on, and Dining Room light to turn something off.
Most of us here advocate doing things as simplistic as possible, even if it requires multiple rules. Some people get OCD about "it MUST all be in one rule", but building and troubleshooting complicated rules isn't always easy, or the best way to do things. Especially for people new to the platform.