First of all, welcome to M5Post!
Singapore Grey is an adorable color and also exclusive to the M5 (and M6) so I'd personally choose it over Alpine White which isn't bad but too played out IMO. Check out our photo threads for
Singapore Grey and
Alpine White. As to interior, I think Silverstone goes well with Singapore Grey while Sakhir Orange might be a bit 'loud'.
BMW put 2 years of development to have the manual transmission fitted perfectly to the M5 so it should be a lot easier than the Carrera GT clutch which is known for its 'trickiness'. Then again, if you don't have to have a manual transmission DCT seems to make a lot of sense for a car like the M5 (don't tell anybody of my fellow 6MT club members I just said that
).
Best regards,
south