so in this post i will write populaire questions and answers that can help you knowing the difference between the custom firmware and the normal firmware and which is the best for your iphone .
Q: On which version of iphone can i use custom firmware ?
A: You can use custom firmware on any version of iphone (from iphone 2G to the last iphone ).
Q: What's the difference between the normal firmware and the custom firmware ?
A: The difference between the normal firmware and the custom firmware is that when you update your iphone using normal firmware you will update also the Baseband (Modem) of your iphone. But the custom firmware update the version of your IOS without updating the baseband and this can be good for closed iphones .
Updating with custom firmware can make opening the network of your iphone using ultra snow possible .
Q: That's mean i will use the IOS 6.1.2 with Baseband 10B144 ?
Q: Can i create a custom firmware with myself ?
A: Yes you can do it using Snowbreeze , Pwnage tool ...
Q: I'm worrying in creating a custom firmware , can i download custom firmwares online ?
A: Yes you can download custome firmwares online : download custom firmwares
Q: After downloading (creating) custom firmware should i update or restore ?
A: You should restore and for your files you can do a Backup before the restore .
Q: How can i know the version of my IOS if it's not Activated ?
A: you can by using the old QuickPwn
Q: Which version if itunes should i use to restore with custom firmware ?
A: it's the same but always the latest version is better