Yes, if you restore your iPod or iPhone on iTunes it will delete Cydia. The restore function on iTunes restores your iPod or iPhone to its previous settings.
To get Cydia on you iPhone, the phone will need to be jailbroken. It depends on what generation iPhone you have and the firmware installed. Every iPhone on 4.1 can be jailbroken using pwnage tool, redsn0w, greenpois0n, or limera1n. I personally have an iPhone 3GS with 4.1 jailbroken with limera1n. Cheers
No it does not. All apps from installous are free but you will not be able to sync the apps into itunes. you will not be able to sync unless you delete the apps. If you get appsync from cydia you can sync apps without deleting.
Jailbreak your iPhone
you go on a website called jailbreakmatrix
Yes but your iphone has to be jailbroken and have Cydia.
You'll have to open cydia 1 more time and install Cydelete
I believe it is the same thing.
you can not reverse the sync
You can sync your iPhone to iTunes to transport music, pictures, videos, etc.
You can sync your iPhone to the Nook app including your bookmarks and other pages.
This page explains How to Sync iPhone to Outlook http://www.sync-iphone.com/contacts-calendars-email/sync-iphone-contacts-to-computer.html