/TL/DR:
no
yes
no, you could absolutley (for example) modify MLR to also play a supercollider synth and use it for input into the sample chopping. MLR uses only the built-in buffer manipulation functions of the norns DSP backend. this process even runs on different CPU core from supercollider process and wouldn’t contend with user synthesis engine for compute resources. (well, except RAM.)
you can also make engines that do many things at once. they are just supercollider classes and SC is very flexible.
the scripting side can also be approached in a modular or chainable way. we haven’t seen a whole lot of this b/c it takes a bit of care and intention to encapsulate data in a lua program. (that said, i tend to automatically keep app state in a dedicated object as general good practice.) but it’s entirely possible to refactor a few scripts into one, some have been already structured as libraries that you can add to other scripts. (e.g. Tunnels).
speficific example, grid control is enabled by defining a global handler and refresh function. swap functions to swap modes. simpler than in Max.
now, all that said… if you want a specific thing to happen, you may need to implement it yourself, or find someone to collaborate with who is interested in the same specific thing.
norns is also not a very strong computer compared to your laptop or whatever, it has minimal UI bandwidth, and it might not make sense to treat it as an entire studio.