Should I upgrade to iPhone 5 or wait for the upcoming model?

I read all over online that in September there will be a new iphone coming out (perhaps the 5s)
I'm eligible for upgrade now so i can get iphone 5 for $200.
I'm in need of new phone because my current iphone 4 give me problems with screen, it's all bright white light, I can barely see anything. I had the problem for about a month now.

I don't want to fix my phone for the second time which will cost $60.

I can fix it, use it till september, then upgrade to iphone 5s, and sell the 4th one (my current one)
or should i upgrade now?

thoughts please and thank you.

Do i have to update firmware to use cydia?

I have an Iphone 3G that i'm gonna be jailbreaking it is running IOS 4.2.1 with the firmware being 5.1.5.04 if i update it to 6.1.5.00 will i be able to restore it if anything goes wrong with the jailbreaking i'm not worried about the warranty since it expired and its basically being used as an ipod. Also do i even have to update it or can i just leave it alone and still use cydia

Added (1). I'm not going to be buying a newer Iphone for awhile as this one is working fine for me

Added (2). Yes that is what i mean do i have to update the baseband in order to even use cydia

How to download apps on iPhone?

I want to know how to download apps on the iPhone 5 and also I would like to know how do you uninstall apps and how do you move the apps around?
Please and thank you.

How to apply for McDonald's jobs on my iPhone?

I did it a few month back for one of the nearby resteraunts and wasn't employed, but now my mate who has been with his branch for over a year has put a good word into his manager for me so she's looking for my application, only problem is, I've forgotten how to do it! Help!

Ps I'm in the UK not US

Added (1). It doesn't make a difference if I apply via iPhone or laptop/PC. The employers won't be able to tell the difference. Aside from that point l, I don't have one that works well enough to do it on. I always use either my iPhone or blackberry for these type of things.

Not receiving any texts, on Tesco mobile?

I'm not receiving any texts people are getting mine and i can call out and people can call me its just i'm getting no ones texts is anyone else having this problem, i'm on an iphone 5, is something up with tesco mobile at the moment?