16 years old, 61kg or 134lbs last time I weighed myself (a while ago :/, scared of water weight from recently changed diet) light activity, and I'm about 5'5".
I use small, silly girlyweights in a 40 min Gunnar Peterson workout once a week because I don't have any heavy ones. I'm worried I might have lost muscle mass from the admittedly too-low calories I've been eating for a few months, which have also caused me to plateau and I don't think this 'routine' is helping (used to do it more often though). I have recently increased to maintenance or a bit under, really, as I'm struggling a bit mentally.
Anyway, I want to start heavy lifting and I have some questions:
First, is this at all a good idea for me?
Where can I get weights?
How heavy should they be?
Can I get heavy hand weights and do the same routine?
And no, I'm not afraid of getting bulky. 
Bump.
I think I should check the time in Americaland before I post next time.
Yeah, it was middle of the night for us. Plus, lots of people have today off because tmrw is the 4th.
Original Post by cjkl:
First, is this at all a good idea for me?
Where can I get weights?
How heavy should they be?
Can I get heavy hand weights and do the same routine?
Yes, it's a good idea, esp if you are eating enough now.
I don't know where you are, but at most sporting goods stores in the States, they have adjustable weights like these. Those can keep you busy for a while, most likely. If you have room, you could also get a squat rack and barbell, but that will be more expensive. If you don't have a weight bench (and don't want or have room for one), an exercise ball can be useful.
I do recommend that you get the adjustable, rather than trying to buy all sizes of individual dumbbells, esp. since different exercises will need different weights.
Most exercises can be adapted for dumbbells - check out exrx.net for help on that.
Check out the Fitness FAQ stickied post, for Melkor's list of lifting programs and also how to workout without equipment (Your Body is a Barbell is one option, if you decide you don't want to buy anything).
