Its 460 - liter (16.24 cu ft) capacity swells to a volume of 1,365 liters (48.2 cu ft) with the split rear seat backrests folded down. (ausmotive.com)
Folding rear seats and front seat backrests with adjustable bolsters are optional. (automobilemag.com)
Can't help you with sizes, other than noting I found lots of Torx screws, including a Torx T25 for the rear seat backrest in an Audi A3. (mechanics.stackexchange.com)