For the Disney Infinity games, you have to get the new Disney Infinity bases that come with the new games, otherwise they won't work (the game or new characters). So to answer the question, for 3.0 there is not an option to get get the game without a starter pack.
No, you will not be able to play Disney Infinity 2 sets on Disney Infinity 1.
Any children aged 10 or over should be fine to play Disney Infinity games although younger children can play with parental supervision. They can be played on games consoled including the Xbox 360 and Playstation 3.
No, but Disney Infinity 3.0 does
Disney Infinity - 2013 VG is rated/received certificates of: Singapore:G
Disney Infinity toys should be available at online retailers such as Toys "R" Us, or Amazon. Alternateivly, you can try browsing through the official Disney Infinity website at infinity.disney.com
Disney Infinity figures are available from www.amazon.com, www.toysrus.com or from the official Disney Store at www.disneystore.com. Individual figures typically cost between $13-$17.
No
yes
There are many retailers for Disney Infinity toys. Most department stores carry them as well as toy stores and game stores. At infinity.disney.com there are links to many retailers as well as more information about Disney Infinity.
September 2014
No because Sonic the Hedgehog is not a Disney property.