I'd recommend the Yorkville Excursion for your PA. For a mixer I'd look at the Allen & Heath MixWiz 12:2.
The Excursion provides all the power you'd need, and the MixWiz provides all the I/O you'd need for your guitar(s), trax (computer) and processing. Racking options for the MixWiz depend on what other gear you'll need that's rack mountable.
Even though you're playing small coffee shop type venues, you still need a good system with some dynamic punch to cover the frequency range of your trax.
Don't forget interconnect cables, etc.
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