I agree that the IOC should hold this at an odd-numbered year. It'll be hard for the participating countries, the IOC, media, etc whenever the youth Olympic games will coincide with the summer Olympic games (assuming that the youth games will be held during the summer, too).
Regarding the eligibility/qualification of athletes in the youth games, so does it mean that the participating countries will be sending their 'second-best' athletes? I'm thinking that these countries will send their best under-18 athletes in the 'adult' Olympic games. Again, this will be a concern if both of these games coincide with each other. I think that this youth Olympics will just end up as a training ground for four-year-interval Olympics.