Yes you can do it with any apple device
sync the iphone with itunes
If you just recently got a new iPhone 4, connect it to iTunes and iTunes will identify it as a new phone. If you have previously synced your iPhone 3G with that computer before, then iTunes should give you the option to sync the new iPhone with a backup from your latest iPhone 3G sync. When you do that, your files from your 3G will be transferred to your iPhone 4. Hope that helps :)
Yes, simply sync it using iTunes.
Sync it with a computer and restore it to its factory settings.
you can set any ringtone in iPhone . but it should be M4r format . just convert and Sync to i tunes . it wil come on the top part in iphone ringtones
No, you will only lose like your music, photos, ringtones, contact and what ever iTunes offers to sync. Restoring to a previous backup can probably lose your jailbreak. Restoring your device completely removes your jailbreak.
iPhone 3G S = iPhone 3G + Extra's
No. It can use your 3g
The iphone 3g is the third generation iphone , is that what you are asking
Apple invented the iPhone 3G.
Both the iPhone 3G and the iPhone 3G S support MMS with the 3.0 update.
iPhone 3g is capable of 3g access, but not iPhone 1st generation. However, some areas do not have 3g coverage, so iPhone will automatically switch to EDGE. iPhone 1st generation only has EDGE and Wifi, and iPhone 3g has EDGE, 3g, and WIFI.