Having used many USB 1.1 devices on USB 2.0 ports I can say that this has never been an issue. What I always run into are people who move a hard disk with OS to a new system and get to sort out motherboard drivers and more.
http://www.usbman.com covers this topic here and there.
In direct answer to your questions: No and I don't know.
I want to purchase an ASUS MB (P4S800) with onboard USB 2.0 ports. I have a Canon digital camera (A70) that I can only connect to a USB 1 port. I have a SIIG RAID controller with four USB 2.0 ports on it and the camera does not function (it fails during the detection process)when connected to it. The Canon website says USB 2.0 operation is not guaranteed. Can one or all of the USB 2.0 ports be set to act as 1.1 ports so I can still connect my camera? How do I do this? Any help with a workaround would be appreciated.
Thanks
Blake

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic