Well logging in has to do with cookies and tons of threads on this
I would suggest your forum and photopost use this as cookie settings. You can edit photopost settings in phpmyadmin settings 171-173
cookie path /
cookie prefix bb
cookie domain .rangefinderforum.com
In your config-inc.php file of Photopost make sure you have your correct vb
license number entered in the $vblicense variable. This must be correct you can find this out by viewing the top of your vb
config.php file in the includes directory.
As far as integrating with header and style of vb
you just need to enter the correct server paths and urls to the forum and photopost and turn on the integration.