Hi A.,
My 18 month old was in casts for the first 8 weeks of her life (born with bilateral clubfoot), then in shoes that were connected by a bar for 2 months, and then when she was about 10 months, she had casts again for 6 weeks. when she wore her shoes with the brace, we had a funny response ready when people asked: we said she was a Pro-Snowboarder in training (because the angle they held her legs were like snowboarding. when she was in casts the second time sometimes if someone asked what happened to her legs i would just say "snowboarding" and nod and roll my eyes a bit like 'kids nowadays, whew' which was funny because she wasn't even a year old. they were confused but that's what was funny.
If we were going to be out in crowds a lot sometimes I had her wear leggings over them, people don't notice as much, and if they are really cute they tend to smile instead of cringe from seeing big bulky casts. not sure if you little boys casts will be too big, but check out http://www.babylegs.net/ there are some cool funky designs for boys too.
I really hated when people felt sorry for her (ooooh poor baby, what happened?) and once got advice to tell them that she was a LUCKY baby, lucky that she has such good doctors who can "fix" her feet.
It sounds like it may be a very challenging time for you and your son, if there is anything I can do or you need advice or to vent, please contact me. Remember that time goes by so fast, and just keep looking forward to the final result!
Ali