speaker and interconnects, how nice do I need

I second JW Audio. I have his interconnects and love them. His speaker cable is ridiculously cheap.
Also consider DNM and anticables.

I concur with the recommendation to start with Canare 4s8 or 4s11 as a baseline for further exploration, if you feel you need to. Buy whatever length you need from some place like https://www.markertek.com/. Don't bother with connectors at first, just twist together the white and red conductors in each cable and connect the bare wire to your amp and speaker terminals. Listen for a good long time and only then begin to explore if you feel it's necessary, or interesting. 

sam-

entry level Transparent will get you started and would jive well w/ your system.  Your listening experience will grow and get better as you advance up the chain of cabling.

I can say that as long as you buy a robustly built connector, you’ll be fine. Cables are a nasty part of this hobby with many thousands of dollars, in my opinion wasted.

balanced power from companies like Equitech or Running Springs will do more then some snake oil vodoo cable ever will.

wire world sells a very nice entry level interconnect. The key points are (1) built robustly (2) adequate shielding to prevent your cable from acting like an antenna (3) in lengths that are the absolute minimum needed.

ground noise and hum can be fixed with devices from the companies listed above. Those key points are also applicable to power and speaker lines with one exception.. Use 10 gauge speaker wire. That's good for anything you'll be using for power.

good luck