Manual tranny is an easy answer - GM wanted to sell the grandprix as a family car and keep the Fbodies as the sports platform back in 1997.
Plus, from past experiences, GM knew manual sales would be low and it wasn't worth it - costwise - to R&D a new FWD manual that could handle the L67's huge amount of torque.
As to most of what you posted - I believe most of your requests were in the G8 and G6 show cars. The G8 has the LS V8 but the G6 has a SC V6 if I'm not mistaken.
AND from current car rumors, the G6 will be making it into production (in some form) as the replacement for the Grand Am line under a new name (Grand Am will disappear like the Olds and Malibu).
_________________________
Regards,
Chew
2007 Sly Silver Pontiac Solstice GXP