Training regime?

Hi, I'm going to join the Royal Marines in 2 years time and I run 3 miles, every time I run.

Here's my overral training regime: 

Monday: Running for 3 miles
Full body workout/Compound exercises

Tuesday: Running for 3 miles
Rowing for 30 minutes
Swimming – 10 lengths of freestyle 
10 lengths of breaststroke 

Wednesday: Rowing for 30 minutes
Swimming – 10 lengths of freestyle
10 lengths of breaststroke
Full body workout/Compound exercises 

Thursday: Running for 3 miles
Rowing for 30 minutes
Swimming – 10 lengths of freestyle 
10 lengths of breaststroke

Friday: Bergen workout 
Full body workout/Compound exercises

Saturday: Swimming – 10 lengths of breaststroke
10 lengths of freestyle
Rowing for 40 minutes

Sunday: Rest day

I'll vary my running routine in two weeks time, as I'll be running for a month then and my stamina would be better.

Is this routine fine? I'm not trying to get any aesthetic goals, I just want to be fit as I'm happy with how my body looks.

I would love to get my 1.5 mile times down to 7 minutes by the time I'm 18 (I'm turning 16 in November).

My questions:

Is my training regime good for my goal? 

Can I bring my 1.5 mile time, a measly 16 minutes, down to 7 minutes in two years?

I eat normally like most people in the UK, I don't have a healthy diet. Will this affect my performance, as I'm assuming that fitness and being healthy are different things?

Hopefully I can run a 5k marathon in January, will this be possible?

Thank you, Akshay.