Hi Vince... can't say I've heard of this brand before.. but then I'm British, so.
.. But the way you describe them and the fact they have to be applied with a brush, I would think they are very soft and powdery... there are some brilliant soft pastel artists here, e.g Gaka and Crumby who work applying the pastels with folded piece of tissue paper, so the brush method could be similar..... do you crumble the pastel and then dip the brush into the powder, or roll the brush over the pastel?
As for underpainting... in the past I have used a watercolour underpainting then applied the pastels over... alcohol yes can be used to apply pastles..... rd2ruin has used this method before, Ipersonally havn't so can't help there.....sorry not much use am I.
....but then I'm now into oil pastels... have you tried those?
Sorry can't help more on this... maybe some others will be able to.