Gamefly will typically send the first game in your Q. However, if the game is unavailable they will send the next available game. You might find troubles getting the New Releases if you haven't added them to your Q early enough. I remember I had to wait over 2 months to get Dragon's Dogma when it first came out.
I don't think you get a case when you keep a game. I've never kept a game but I do believe the price is discounted because you don't get the case/manual. All you get is the game in the sleeve. Again, not positive but it seems like that would be the case. No pun intended.
Not a lot. I bought one at a yard sale like 3 years ago for 20 bucks. It had 2 controllers and 8 games. Having the box/manuals/original materials and very little cosmetic damage will increase the price. I suggest going to Ebay and searching for the gamecube and go from there.
Unfortunately I don't think its possible without hacking your device, which is illegal. I do have some examples of games that allow you to save whenever you want. The Elder Scrolls Series (Oblivion is the most light hearted of the series), Dragons Dogma and Fallout (depending on his age, this game might be too mature for him). Lastly, Star Wars The Knights Of The Old Republic series is a great one! These games are for the first gen xbox but they do work with an updated 360. They are wonderful games that delve deep into Star Wars lore, taking place 1000 years before the events of the Star Wars films. They are slightly darker in tone but are more child appropriate than some of the other titles I mentioned. No profanity/blood/adult content. I hope this helps!!!!!
Dragons Dogma, lvl 35 against the Drake in Hellfire Grove. I spent a half hour battling this beast down to his final two health bars when guess what? He used his death roar to kill my team and I found myself without any spare healing items. I nearly cried! I eventually went on to defeat him at level 45 but it had become far too easy. Another moment was in Oblivion when I came, underlevelled, to the palace of (can't remember his name) in Paradise. I walked in there ready to hack and slash and instead I was totally demolished by him and his goons!