How much have you looked for answers to your questions in the manuals?
Some of your questions also involve how to use whatever DAW you are using. Like this:
Like, how do I program the pads on the controller to play percussion while using the keys for a lead synth or piano?
How do I use different midi channels so I can perform live and record different sounds on the pads vs the keys, and how do I split the keys between two software instruments?
It's all about setting the midi channels you wan't both on your DAW and your controller. I think the controller allready by default is set to use midi channel 10 on the pads, and user channel on the keys. I'm not sure, as i don't have the controller. But read the controller manual about setting midi channels.
The rest is about how your host/ DAW work. I don't use Logic.
More advanced: Eventually I'd like to know how to record a group of tracks in Logic and then program a pad on my controller so when I press the pad, it starts the entire group of tracks I pre-recorded. How do I go about this? I could see making some ambient tracks and grouping them together so I can trigger them live with a single pad.
You can use the transport bar to start the DAW, if you have set up your controller to control your DAW like you can read here:
https://www.arturia.com/faq/keylabessential/keylab-essential-tips-tricksThe rest is about the possiblilities your DAW have. I can't tell what's possible in Logic. I suggest you ask in Apple forum and Apple support.
In generel i also suggest you look in the manuals.
You need patience and some studying. That's normal.
There are coarses on the internet for Logic i think.
If you have individual questions about Arturias products anyway, then feel free to ask in this forum and Arturia support if needed.