rrrarrgh! he is super! definite hint of mishcief in him though too by the look of it although that is the best way!!!
yes to scent if you can bring something Bruno has slept on home to Bebe, groups of cats have a family smell so if she is familiar with his smell she may think he some long lost nephew already. you shouldn't need to keep them separate for long, especially as its difficult in your house. kittens make adjustments to new things very quickly, although Bebe might want him out of the way sometimes. i wouldn't leave them together unsupervised until you are sure they are both happy. but with a kitten and an adult it may not take long at all. Let Bebe have a high up place where she becomes invisible as Bruno looks like he may be a maniac for playing!
he will be ok if he leaves his mum and sibs a bit early but he will miss out on some learning. Bebe will teach him a lot too but she may not be that interested and kittens learn so much about manners from their brothers and sisters (mainly it hurts when you bite!) we have known some ill-mannered cats who have been unfortunate to grow up as only kittens. i know its not really your call but if you could drop a hint like 'i hope he can stay with his family until they are all 10 weeks (say 8/9 if you think 10 is pushing it) but if his siblings have gone early too of course we will pick him up' sometimes people think that because a kitten is weaned its ready to go and also that because a mum has got fed up (and they sometimes do when the kittens are around 7/8 weeks old) they are good to go. They are OK its just better if they stay a little longer. If the mum cat is going out she will get pregnant again as they can get pregnant when the kittens reach about 5 weeks old and her last 'boyfriend' will surely know where she is! Again its not your responsibility but if you think she is not aware then maybe let her know. I do realise that you don't want to atagonise the owner when she has your baby
can't wait for the bruno and bebe together photos xx