How long will 500mb data last on an iPhone 4s?

I might be getting an iPhone 4s on contract but I don't want to pay too much so at the minute it looks like I will go for the 500mb of data plan, so will that be enough and will the internet just run out when I have used it all (I will be going on Orange/EE) or will it charge me? I will probably use it for twitter for maybe 5 to 20 minutes a day (I have Wi-Fi at home, I'll probably use it on the bus) I will try and be careful but how fast will it go?

Will the iphone 5 be 4g on three?

I have been reading online that the iphone 5 doesn't work on vodka phone and O2 4G for some reason… Is this the case with the network three as well?

How to change the background colour of my whatsapp on my iphone?

I have a iphone 4, and my whatsapp has always had that white background on the chats, but I saw my friends and its black she told me she went into settings and changed it. I went into settings on whatsapp but couldn't find it do I went into the normal settings but couldn't find whatsapp?

How to improve my iPhone battery?

I have an iPhone 4S, and within 5 minutes of playing a simple game or an hour of leaving it on standby 20% of the battery is going. How do I improve this? (and I don't want any of that 'turn down your brightness' stuff, it dosn't really do much)

Hide downloaded apps IPhone 4S?

How can I hide downloaded apps ( Facebook, tumblr, Instagram, snap chat all those apps ) without jail breaking? I want to be able to access them quickly but not have other people that are on my phone see them

What can I do to fix my iPhone 3GS touch screen?

I dropped my iPhone 3GS from about chest height and it turns on and charges fine. The only thing is the touch screen is not responsive. It still lights up and works, but it won't respond to touch whatsoever. The power button and home button still both work. Are there any suggestions on how to fix this? What parts will I need to buy to fix it?

IPhone in 2 Years Contract in USA in $199?

What is the meaning of this. I'm from India and you have to pay almost $850 Dollars to purchase an iPhone. Seems like iPhone in USA is pretty cheap.
What is the meaning of contract and why they are asking for very few bucks.

Added (1). IPhone 5s in $199 with 2 years contract?