Hiding some text and lightbox

Hi, just two very important features I can’t seem to find in the documentation. Is this possible?

—blog post—
Public text goes here, “bla bla”, with thumbnail pictures and their full size…
Then a text shows, “Only members can view full size pictures below”, which should dissapear if logged in as a member.
A section follows showing only thumbnails to non-members! Those logged in on the other hand, would be able to click on thumbnails and get a lightbox.
—end—

In other words, can you hide some text (“only members…”) for those with membership and hide code (link to full size image) for those without membership?
Thx.