Including external Pages / Selecting Text Fragments

Hi,

I have a complex and twofold question: I want users to specify external sites, a) include them, and let b) users annotate certain paragraphs of text.

a)

As this sites are external (not on the same domain) I cannot use iframes since I cannot select text then, as I understood, right? So I need to create a proxy page which integrates them in the local domain.
If this works, I guess the problem are relative urls - does anyone know a good way to correct these?
Furthermore, do I need an iframe, or is there another way?

b)

I would like users to be able to select text paragraphs and add a description. Ideally I would get XPath for the selection. Is there a jquery  tool/plugin to do this? Like select some text and get the XPath for it?

I would be very thankful for any input
greetings, Christoph