[JDHill]

When using Real Scale, a texture's input values do not take the document's working units into account - that is, Tile/Offset for Real Scale-enabled textures always mean an absolute number in meters. The document's unit is taken into account when the plugin modifies the object's mapping though - so when you have an inch-based model and you specify a Tile size of 1cm in a Real Scale texture, the texture's size will be converted to inches when the plugin modifies the corresponding Rhino mapping - the texture will show up in this inch-based model at a real size of 1cm. If you then apply the same material in a model which uses feet as the working unit, the texture will still be shown at 1cm.

I'm not sure I understand the second question, but the relationship between Real Scale and a texture's Channel is this: Real Scale is only allowed for textures which use a Channel number of one or greater. Channel zero is reserved and always gets whichever mapping happens to be visible in the Rhino viewport at the time of export. The viewport mapping is also used whenever an object's material has textures which specify a Channel number for which there is no corresponding texture mapping assigned in Rhino.