Password-protecting with session/cookies/other techniques

Hi experts,

I need to password-protect an area of my site. This will include (1) a ‘sub-homepage’, where excerpts from various post categories are pulled (i.e. a page); (2) pages linked to from a unique menu on the sub-homepage; and (3) the full posts linked to from the post excerpts.

I understand that posts can be password protected from the write post area, but I would like to somehow use a session/cookies, whereby user is prompted for the username and password only once (a single username/password combo for all users is fine).

I have limited experience with this, but the best way I know, is to house all of these pages in a .htaccess-password-protected directory on the domain.

Is it possible (i.e. is there a plugin) that allows one to mark certain posts/pages to be stored in a specific directory?

If not, would it be best for me to create a second WP installation for the password-protected content, and if so, is it possible for me to pull posts/excerpts from that second installation into pages held on my first installation?

I appreciate that this is a long request, and am hoping there is someone out there that can give me some guidance.

Thanks experts!

– John