[Plugin: WP Super Cache] Debug messages

I’m working through debug errors and notifications for the plugins I’m using. Could you please review and correct your plugin code or reply with a configuration change if this is on my end.

Loading Admin:
(occurs twice) Notice: Undefined index: wp_cache_key in /home/mywayso1/public_html/.WordPress/wp-content/plugins/wp-super-cache/wp-cache-phase1.php on line 255

Warning: session_start() [function.session-start]: Cannot send session cache limiter – headers already sent (output started at /home/mywayso1/public_html/.WordPress/wp-content/plugins/wp-super-cache/wp-cache-phase1.php:255) in /home/mywayso1/public_html/.WordPress/wp-content/plugins/wp-e-commerce/merchants/paypal_certified.php on line 788

Loading Main Page:
Same as above and this warning
Warning: Cannot modify header information – headers already sent by (output started at /home/mywayso1/public_html/.WordPress/wp-content/plugins/wp-super-cache/wp-cache-phase1.php:255) in /home/mywayso1/public_html/.WordPress/wp-content/plugins/wp-super-cache/wp-cache-phase2.php on line 71

http://wordpress.org/extend/plugins/wp-super-cache/