The dumbells wouldn't be much use on thier own, because there's no variation of the weight, so you'd be underworking certain areas, but potentially working some areas quite well, but that would allow for no improvement in what you could lift.
I'd suggest doing bodyweighted stuff, as your strength could increase anyway as you go.
So you'd be looking at something a bit like this.
Squats, 2 sets 10 reps
Lunges, 2 sets 10 reps
Good mornings, 2 sets 10 reps
Bent Over Rows, 2 sets 10 reps
Press Ups, 2 sets 10 reps
Shrugs, 2 sets 10 reps
Planks, 1 minute
The treadmill would work doing a basic interval setting for 30 minutes.
I'd suggest you work the bodyweight routine in with the Cardio like this.
Day 1. Body workout
Day 2. Cardio
Day 3. Body workout
Day 4. day off
Day 5. Cardio
Day 6. Body workout
Day 7. Day off
As for the diet, you could do something like this.Breakfast
Bowl of Cereal + Scrambled EggsSnack
Small Portion of Peanuts + an AppleLunch
100g Low Fat CheeseDinner
Whatever is madeSnack
Beans on Toast, 1 slice of Toast.
Hopefully this gives you some ideas