I uploaded a photo to my profile. When I click on my "preferences", the photo is displayed with edit and upload links. However, no photo is displayed in my member profile page. I have both $guestShowThumbnails and $guestShowFullsize=TRUE;

Be sure you have correctly specified 'user_custompics' field (or however it is called) in $dbUserSheme. It is important that you specify correctly the numerical index for that field. Run determine_fields.php if you're in doubt what number it has.

Got it fixed! Although I had specified the field correctly in $dbUserSheme, I forgot to include the new field name in $customProfileList and hence it was not showing.

Well, if you have $customProfileList specified you should include the field there of course :-)