I read an interview with a Fender Custom Shop guy where he recommended using carnauba wax on sticky feeling nitro-finished necks. A couple of applications should see any sticky feeling disappear. Apart from that, no need for it.

I've thinned TruOil (in my one failed attempt to do a TruOil finish) and it does lower the surface tension a bit and so make it easier for the TO to fill small cavities without simply following the previous contours. Also, the TO does tend to thicken as the bottle empties, so adding a small amount of turps to a half-empty bottle can get it back to the original viscosity. The downside of thinning is that your layers are thinner (well less actual TO content per wipe), so you need more applications.