Yes keep standard box. No you wont get anything top end, think there has been MOT problems with some members cars with 6 speed boxes also (it catches on some of the body or something like that IIRC) rendering it a fail.
Have a look on forum its very well documented why the six speed box is not as beneficial as the standard 5
keep up yes, pull away from and leave behind probably not, they will probably have you top end as well.
They maybe might leave you in the corners as you will be fairly nose heavy, and no weight in the back also, in fact you might only be any good on a straight flat road in all honesty but we will see
as above, but i am guessing the saxo isnt standard either because they all arent