Custom box inset and custom bullets

[Nick Bell]

Dear list,

I have looked at the mailing lists and wiki but can't find what I want. 
What I'd like to do is:

(1) to create a module defining a new box inset type with an oval frame 
and framesep=12pt, space between lines=medskip, which I can then apply 
to bits of my documents.

(2) Also I'd like to know how to change the bullet type for each 
individual line (itemize environment) - using renewcommand?

Thanks for any pointers

Nick