I see no one has answered your question so I will take a jab at it. Anyone with more knowledge please feel free to correct me
1. No
2. There aren't any.
3. Only if you pull the cable out during the upgrade process
From what I have read the 2.05 bootloader changes the partition size of the EXT rom so you have more program space. This is good which gives you a couple more megabytes of program memory but most kitchens choke on this. Personally the downgrade procedure is not that difficult and scary. I'd recommend you do it.