yes, you can just use wifi access to use the Internet on your iPhone
YES, It's free. but just can use at apple product. for example: iPhone 4 , iPhone 4S, iPad touch, Recently At&t added Free Facetime over 3G before it was only offered on wifi. Source of info is added below in links
No. Use of the GPS is free.
Technically no using wifi is free but paying for the wifi costs money (Apple doesn't charge you but in order to get Internet you will need wifi to go mobile which will cost the owner money.) I use my next door neighbors they don't mind.
No you do not need WIFI to use the iPhone. The iPhone works with either 3G or WIFI. Some apps require WiFi to download or run depending on their size. I find wifi works best though and is faster. YouTube videos are extreemly clear and crisp with wifi.
If it is wifi then no it does not use your credits.
Yes, you can use your iPhone 3G(S) to access the Internet if you have an available WiFi connection.
Wi-Fi is free to use on the iPhone. If you know the password of the Wi-Fi or it is unprotected. There is no cost to use Wi-Fi through the iPhone but there maybe a charge if you use Wi-Fi at a coffee shop (or place like that).
Yes unless it is your WiFi you are using so technically you are still paying for it
no you can use the mobile network for Internet
Yes or public wifi
it will obviously, any use of internet (if you own it) you have to pay for it. Actually it depends on how long you use the PSP. Well, my uncle said if!!!!!!!! you have the iPhone on your psp he thinks it costs money but i don't know. internet is free to psps provided the wireless connection your trying to use isn't password blocked.