I cannot reproduce your second problem. I can make brushes like I wish in the way you describe, save them and use them ad infinitum. I have version "a".

As for the first problem: Xara makes a difference between dynamic and passive attributes. Dynamic means in this case: linked to the blend tool. As long you read BLEND down left, you are in DYNAMIC MODE;

What you do is:
1/ you group to keep the relative places
2/ in the ARRANGE menu you CONVERT TO EDITABLE SHAPES. You now lose the dynamic blend attributes but
3/ while holding CTRL down, you can select each object separately now and give a contour, change fill etc.

success. [img]/infopop/emoticons/icon_smile.gif[/img]