You can copy and paste into the Add response. Many people use this to paste a url link, which becomes a 'Click here'.
As for attachments, this is not possible on the forum, it's not geared up for it. It would require a vast amount more memory than just text.
Do you get any free web space with you ISP? You could post an attachment to that, and post a link on here.
Can't help with the disk.