Are these wrappers available or are they still work in progress?
Yes and yes. If you are working with the mojoportal source code (most up to date is svn trunk) these controls are in the mojoPortal.Web.Controls project and can be used outside of mojoPortal. I blogged about my work with ExtJs briefly here. In the post it links to this example .NET page, and from there to this html page that shows what the source of the .aspx page looks like to see how to use the controls.
Would you consider that layout as a new skin type and place your content within each of the portlets or something else?
No I would leave the existing skinning system intact as it is though it may not be used in the "portal page". My thinking is that there could be an option to make the MyPage (or its ExtJs portal page replacement) the default page so that those who wnat to make the portal style page their main content can do so but those who prefer the more typical design and branding of html can use the current setup.
p.s. if I want to make a small donation does the paypal donate function work and the correct way to go?
absolutely! I appreciate any and all donations and so very few people actually donate, I wish more would.