Here is my site, I have 3 paypal buttons on my site:
http://shatteredthought.com/ShatteredThought/Buy.html
What I did was this, in iWeb, where the buttons are located I put this text:
INSERTCODEFORBUTTONHERE
After I published to a folder, I used my html editor (BBEdit from Transmit) and Found that text, and replaced it with the appropiate code from Paypal.
As for your other question...RSS and IE (internet Explorer) do not mix!! They will need the new beta version of IE 7 to take advantage of the RSS feed, or can download an RSS reader from yahoo or other company. If they user firefox, or opera they can subscribe.
Basically, IE was behind on the times (I say was because the version that comes with Vista will support RSS Feeds) so for now they will need another browser.
They'll love firefox anyway.
Hope that helps you.