Is this a problem due to me using 3.5 and the brush coming from v4
It could be; new brush modifiers are added and changed all the time, and as of tomorrow you're going to be 4 versions behind.
If its the same Orb_Cracks brush I just found (the thumbnail is the same but the alpha looks different), then it has the roll_distance set to 10: lowering the value will produce a more dotted result (different then what you're showing, but I don't think 3.5 even has roll_distance to begin with so that could certainly throw things off).
Your stroke modes also don't appear to be grayed out in that picture, only the 2.5d ones since you're editing a 3d tool and not the 2.5D document. Unless you mean the stroke palette, in which case I suppose it could again be due to the fact that the brush may be expecting stroke-palette options that don't even exist.