The film advance "problem" is a weakness of design. It's plastic-against-metal and does wear out over time, albeit not helped by aggressive winding. Pentax makes a point of winding on in one smooth continuous and firm stroke, no jerking or yanking or broken stroke. There are many tiny moving parts in that mechanism and just one needs to break before there is no winding action at all — there is so much interdependence under the skin. Somewhere online is an Engineering and Service Manual for the Pentax 6x7 and 67 bodies which gives you an idea what service folk were up against. The winding mechanism weakness is purported to have been addressed in the modernised (67ii) bodies. As with everything, how you treat it will determine how well you service it. It's a nice kit indeed. The 55mm f4 is the absolute standout in what you have. The 67ii will likely make a better job of exposures shot with a polariser; with the 6x7 and 67 bodies, polarised shots are best manually metered.
Tonight I will develop y first roll with the 55mm F4 lens and I'll post my keepers. As for the stroke and doing the Pentax way; one firm and smooth stroke to prevent any damage.