As far as cleaners, I've tried a load of different ones over the years from dedicated brand ones (e.g. Yamalube, Wako, Motul) to WD-40/Kure5-56 to kerosene, but never found one (yet) which blew me away. Kerosene wins on the price / performance, but last weekend I was using the last of some Yamalube cleaner and 'dry' lubricant (as it's called here) as they were on offer - worked fine and weren't insanely priced.
Same for 'lubricants' too - tried oil variants, drier wax ones and each seems to have pros and cons, but not found one yet to rule them all.
As for rags... been using some paper based ones the local DIY shop sell which work well, and the odd old t-shirt. I'd never thought to wash one though, as I'd be imaging residue in the machine. Have you seen any issues from that?
For brushes, I used fairly soft brushes bought in bulk from the local bike supplies shop, though I did try the 3 way brushes, and whilst they save a bit of time, I'm not massively convinced about them as they gunk up quite quickly I find. Oddly when I was buying some bits this weekend the shop had a big bucket of them on sale, and I was asking if the bristles were too harsh for O/X ring, and the staff said they were fine (to be expected I suppose). I'd be very interested if there was some evidence that they could harm the seals.