Hi chap.
OK, re- polishing with the Menz, this is good for removing swirls by hand, so only needs to be done as and when you feel it necessary. I would definately do it every six months so could tie in well with a good claying. Sometimes claying every 6 months is over kill, but where I live there are a lot of trees + currently road works, so I get a lot of contaminant build up, regardless of protection.
When you say a once over with the plush towel, this is just to remove the polish residues, so should be done panel by panel after polishing.
Natty's paste waxes will last for about 1-3 months, dependant on weather and washing. I applied my Natty's blue pretty much every month, but I have a garage allowing me to do this regardless of conditions/time of year.
The sealent should really be applied before the wax. This builds layers of long lasting protection - the wax is for added looks and beading! A good couple (2-4) layer of Chem Guys Blitz can last up to 3-4 months or so. Best part about a spray sealent is you can actually add another layer as and when you want after washing. This can be spread/applied with a decent microfibre applicator as found on Polished Bliss or any other good detailing website.
Re the leathers, depends on the condition. The soft brush is to agitate the cleaner deep into the leather to lift out grime, then wipe with a damp microfibre. Then you need to protect the leather again. Suggest either the LTT or Gliptone twins.
Hope this helps chap. Any questions, PM or post away.
JD