There is a book called The Men's Health Big Book of Exercises that has a bunch of really good modifications and uses for dumbbells (among other equipment). It's great for variations, and because it tells you how the modifications change the movements while giving you a breakdown of the move with pictures so you can check your form. I have the woman's version, and it's great!
You should check out this book. Its practically the bible on weight training IMO.
The Men's Health Big Book of Exercises
It will give you a ton of tips, show you how to make your own workout and gives good sound advice on eating etc. Im currently doing a beach body workout from the book.
Also it will show you body weight workouts as well.
Protein shakes could be good as a meal replacement. However you need to be careful that they dont add too many calories. if your main goal is losing weight you want to adjust your diet to help to do that.
So after I hurt my back I went to a chiropractor for some help. instead of doing only corrections he gave me routines from this book (links below) to help strengthen by back along with visits to him. Now I know your not injured but there are some pretty killer work outs and routines in this book. The book also shows you how to do each work out and proper form.
Give it a flip through before you buy, maybe you can find it at a local book store.
This is the male version there is also a female version, since i do not know what sex you are. (I assumed a guy)
I also think I saw one for 15 minute work outs, just have a look.
Canada: http://www.amazon.ca/The-Mens-Health-Book-Exercises/dp/1605295507
USA: http://www.amazon.com/The-Mens-Health-Book-Exercises/dp/1605295507
Free website: exrx.net
I ordered this book on someone's recommendation (still in mail, so can't comment on how good it is): The Men's Health Big Book of Exercises. Now I know you're probably thinking the same thing I was thinking - it's by men's health mag so is it any good or is it just a way to sell the magazine? I trust the person who recommended this to me and have seen him go from being skinny-but-unfit to very-fit doing mostly bodyweight exercises and said that this good is good. I am at a point where I need to look up good exercises to design my own workout, so it was the one he recommended to me.
> though some diet stuff wouldn't hurt
I haven't read it yet, but Good Calories, Bad Calories sounds like a good one to begin with. I'm definitely going to read that soon.
Per Mens health big book of exercises by Adam Campbell, " lifting of the heels is a sign off tight hips.... To remedy the problem perform a squat, find the moment in the motion where heels start to lift but still on ground, and hold that position. Do two sets of these. " Also in the book it shows a variation of the squat being perform on your toes, states that it engages your quads more than a normal squat.
Link for the book. Really good read and great guide to your muscles.