Unlocking an iPhone. What do I do?

I was planning on going to a shop or market stall, somewhere where I can get an iPhone unlocked this weekend. The only thing is that I'm not the most intelligent individual when it comes to technology and so on.

The iPhone was previously used by my dad but he upgraded a few months ago, all I'm aware of is that it needs to be unlocked for myself to be able to use it. Do I need to reboot it or anything like that? I've also noticed that there's no way of signing out of the app store which means I'd be using his account instead of my own. Should I import any photos he wants keeping on to the computer due to the fact that I may need to reboot the phone or do I not need to?

Once I have had the phone unlocked will it be available to be used with any sim card, including my current sim which I'm using in my own contract phone?

Also, after its unlocked and if required rebooted, will it be completely unrestricted or will there be some features unavailable to use?

Oh, and finally… How much does it usually cost to have an iPhone unlocked, and will the guy/girl who unlocks it be searching through any private stuff on the phone?

I'm aware that some of these questions might sound quite stupid, but hey… Like I said, I'm not the most technical guy in the world.

Any help is appreciated!

Thanks,

Ben

Added (1). P.S I'm on a different network to my dad if that makes any difference?

I have an idea for a product?

I want to create a system that involves two Bluetooth/ Wi-Fi connected buttons that are small. The buttons would be stuck to a wall/ surface. Ideally they would be two halves that are separated by the inside button. The button would be pushed or just tapped by the user and it would link to a response by the iPhone. Does anyone know how/ where i could have these created for the cheapest price? So MUCH APPRECIATED

Make an Apple ID without a credit card?

I've used my dad's Apple ID for a while now and want to make my own on my iPhone. I was just trying to make it but there's no "none" option where it says credit card and I'm not sure what to do.

How to turn my iPhone back on when my lock button doesn't work?

My iPhone lock button doesn't work and my phone was being slow so I was going to turn it off and then turn it back on. So I turned my phone off and then I realized that I didn't have my charger with me. I know plugging it into the charger is the way to turn it back on but is there any other way to do it since I don't have my charger?

I buyed a Iphone is Apple ID locked so?

I buyed a Iphone which is Apple ID locked so, If I delete all the files in the iphone and can I download new apps with new apple will it gona work? Will cel gona work perfectly with new id r I should change the software?