Cydia itself is considered to be safe but apps that you may download via Cydia will not have been checked (as they are from Apple's App Store) and so may compromise your personal information without your knowledge.
I think it is safe
Yes and no. According to those who did jailbreak their iPod Touch, they say it is safe to do it. Though, the hardcore facts say that is isn't safe because it voids your warranty, and could cause software corruption in your iPod and could possibly make your iPod useless. It is a risk to jailbreak your iPod Touch, but according to those who did it, if you do it correctly it is safe.
What exactly do you mean by safe... Can the iPod touch get viruses from websites? No. Does the iPod Touch have small pieces that can break off and be swallowed by a small child? No. Will the iPod Touch wake up in the middle of the night, sneak through the house and steal your wallet?... I highly doubt it. iPod Touch has stable software that is not invasive or damaging to your computer in anyway. I have been using my iPod Touch 3G since they came out and have never had any problems with it.
It uses an exploit in the ipods security system to install cydia. That's pretty much it. It ranges from pdf exploits to system exploits, but its perfectally safe, and its not illegal. Its usually used by users, hackers, and app developers for windows
it is safe to download audio songs from www.songs.pk a huge collection of Hindi songs..
Yes because I've done it :)
No, you would probably just go into safe mode if anything went wrong. If it does have a problem with not turning back on then hold the volume up button on the ipod to get it into safe mode.
As of today (November 24th, 2010), jailbreaking an iPod Touch is not illegal. Is it 100% safe? No.
Wi-Fi is completely secure for your iPod Touch. It would be best if you have a locked router that needs a password, but it is completely safe.
yes
Yes.. But the hotness that it makes can burn the hardware of your iPod so.. Its your choice...
on an iPod touch, if Springboard crashes, it'll reset your iPod and put it into safe mode. Like a computer goes into when it crashes and you restart it. The only difference is that you can work with ANYTHING in safe mode on your ipod touch, which is necessarily the iPods state after springboard crashing.