You should start off by checking out a relevant repair video via a good source for DS Lite repair videos (http://www.nintendorepairshop.com/). Once you figure out how to repair you need a good source for parts, which this website is good for as well.
To repair the microphone on a Nintendo DS Lite you should send the unit to an authorized repair center or technician.
Take it to a DS repair dealer
you can't you need a modded Nintendo ds lite
Send it in to nintendo for repairs
10-20
yes you can
on a ds at the back it does NT ssay ds lite and on a ds lite it says ds lite
Yes you can. You can also connect DS lite to DS and DS Lite to DSi.
You can't download games for DS lite because you need a game cartridge for the console.
It would be pointless to keep the charger unless you have a second DS Lite with which to use it. The DS series have different types of chargers for each individual DS, so a DS Lite charger would not work with a DSi.
you cant because you need to have your recite if you bought it at that store
Yes, the original DS and the DS lite are 100% compatible with games. The only difference between the two is they both need different battery chargers.