Some basic Exhaust mid delete questions.

Hi All,

Appologies if this sounds amature, i've never replaced an Exhaust on a car yet.

I am after a better exhaust my car's a 2005 and it's looking very rusty!

I have found someone selling a mid delete staight pipe on a facebook forum.

I need need a few questions answering;

1) this is a 3" pipe, is it easy to convert stock (2.5" i believe to 3")

2) I want to pass my MOT without messing about, can I do that with a mid delete system?

3) I need to replace the backbox too any suggestions? I don't want the car to sound like a boy racer, just a little more revvy noise.

4) what backbox can I get that will plug and play with this pipe.

Image attached.

Thanks in advance.