Downloaded iOS 7 ipsw and how?

I downloaded iOS 7 ipsw from redMondpie.com for iPhone 4 and can some help me how to install iOS 7 on my iPhone.
I already have my iOS 7 ipsw on my desktop. I have windows 7, iTunes 11.0, iPhone 4 with 4.3.3.
Can someone help me step by step how to install this iOS 7 ipsw to my iPhone 4 and does it now require Internet as I already got iOS 7 ipsw.

Can you buy an ipohone separately and have tmobile connect it for you?

Basically I want to buy a refurbished iPhone 4 or 5 and cuz I hate the aspect of having an iPod touch and a Samsung gravity cell, and want to be able to play music and do my txt and web all in one. Can I buy my IPhone somewhere else and bring it to tmobile to transfer my account over?

Reasons why I need an iPhone?

I'm 16 years old and I really want and need an iPhone. My parents think otherwise. I know that iPhones are really expensive but both my mom and dad have iPhones. I'm stuck with a phone that I can't receive picture messaging on, I don't get important group messages from people at school. I'm involved in theater and a leadership position in school and I always need to search the internet while on the go or be able to take pictures. My parents are not easy to persuade at all because they think I'm irresponsible, well I used to be, but I've really worked hard in school this year. My grades aren't awesome right now but I have tutors in all the classes I'm having trouble with. I need some other reasons why I should get an iPhone so I can persuade them to get me one. Any ideas?

Transferring to a pantect phone to an iPhone 4?

I have a simple pantect phone, I have unlimited calling texting and i have 6gb of Internet. I have been wanting an iPhone and my cousin said I could use hers because she got a galaxy. I noticed that the sim cards are different. I looked on AT&T and the sim cards are free. If I order one, do I have to go somewhere to get my contacts switched? Or can I do it myself? Lol if so, how can I?

Should I get a 32G 5c or 5s?

Should I get an iPhone 5C for FREE, or a 5S for $100?
(My phone carrier is providing $199)

I currently have a 4S. What do you think?

Is it worth it to get an iPhone 5c?

I currently have a blackberry torch (had it for 3 years). I hate this phone and really want an iPhone. I've been reading about the iPhone 5c and what I found is that the phone is essentially an iPhone 5 but with a different color. People also been calling it cheap since it's made of plastic. I'm stuck on whether I should get an iPhone 5s or the 5c. I don't have a lot to spend since it's my moms money. Btw I'm 16.