Thanks Trogluddite for those observations ! Nice idea to build something from premodeled parts !
Concerning 3D warehouse...I'll definitly not rely on it, too messy for me and most of time bad models...Concerning practical things, I'm aware of SU requisities and I'll not propose any training sessions if PCs are not good for SU.
Anyway, thanks again for your thoughts, they're very usefull !!