Teardowns I've Worked On
Answer to "Why does battery go dead after a few days of nonuse?"It might be the battery aging on you... but you might be in luck. Apple had a battery recall a while ago. You might be eligible for a free replacement. https://support.apple.com/iBook_PowerBoo...
Answer to "Will the new charger design work for a Penryn MacBook?"The newer cords come in either a 45w, 60w, or 85w design. 45w = MacBook Air 60w = MacBook/13" MacBook Pro/15" MacBook Pro (2009 revision WITHOUT 9600m GT) 85w = 15" and 17" MacBook Pro Either a 60w or 85w will work fine with your Penryn MacBook Universally, the MagSafe connectors are the same... but if you choose to buy one, make sure it's at least a 60w adapter.
Answer to "Computer recognizes iPod, but Itunes doesn't"It depends on your operating system... but format it using a utility you'd normally use to format a normal connected USB drive if you're system recognizes it. This will "corrupt" it.... iTunes will detect it's corrupted and prompt you to restore the firmware of the iPod... that might solve your problem.