Multiple issues with one iPhone

I apologise if this is not allowed but I'm not sure what else to do. Recently my iPhone 5c has been having a lot of issues.

Firstly, My phone restarted itself and now when I try to activate it, it says "Your iPhone could not be activated because the activation server is temporarily unavailable etc etc. Please try again in a few minutes" its been like this for a while now and I keep trying it and it just won't work?

Secondly, I am unable to send or receive texts despite having a working sim in my phone, when I send texts it just reads as sending and never goes through, and then I don't seem to receive them either as I have tried with a few people to see if this is the issue, and I just cannot receive them?

Thirdly, I am having the exact same problem with my phone calls, but I am able to receive these just not make them, its not the mobile network I am with as there are no problems there, my sim is fine, I just can't make a call and every time I attempt to, my phone just crashes completely.

Next Issue is my iMessage, for whatever reason it won't stay activated at all, it keeps un-activating itself and when I manage to get it to activate it takes for ages, and then stops working

Lastly,I can't access apps without it Each time I click on an app it doesn't even attempt to load it just crashes! Which is rather annoying because I can't access anything, just crashes over and over again.

Does anyone have any idea why my phone is doing all off this to me?

I do apologise if multiple questions aren't allowed in one topic but I didn't want to make multiple ones.

Thanks