Toes down: Whenever I do it, it means I am gripping with my knee. Not consciously, but I can do it without trying...just a natural, I guess.
When my knee grips, it prevents the weight of my leg from flowing around the horse and into the heel. It also creates a pivot point that tends to lift me in the saddle. Once this happens, I have a hard time keeping my stirrups, so I point my toes down trying to hang on to them. For me, the solution isn't 'heels down', but 'spread your knees, and allow the weight to flow into the heel'. When I do that, my heel will go down and I can keep my stirrups without pointing my toes.
For western riding, my favorite video (and I post this video a lot) is this:
I like it because it is western in approach, and because it emphasizes moving with your horse instead of 'position'. Position sounds static, and is usually 'taught' on a still horse. Position should be changing as you adjust your balance and motion to the horse, and to what you want the horse to do next.
It looks like you naturally balance in a forward seat. I do too, and I don't mind riding a western saddle with a forward seat. Mine is pretty *******ized since I never had any formal lessons in riding with a forward seat. You can find some good books at reasonable prices on how to do it. My favorite is http://www.amazon.com/Common-sense-horsemanship-distinct-schooling/dp/0668026022/ref=sr_1_1?s=books&ie=UTF8&qid=1368286995&sr=1-1 by VS Littauer. It would also be hard to go wrong with anything written by George Morris: http://www.amazon.com/George-H.-Morris/e/B001JP4RKO/ref=ntt_athr_dp_pel_1. Some of his used books run under $5 including shipping from Amazon, and that is dirt cheap!
To condense a forward seat into two sentences: Your heels are forward of your hip, and your body is folded so that your center of gravity is above the stirrup. If you draw a straight line up from the stirrup, about half of the body should be in front, and half behind. That allows the saddle to pivot around the stirrup bars, which also happens to be where the horse's back pivots. It puts your center of gravity about the same as the horse's. I find it very good for going fast, but too tiring for just a relaxed ride. George Patton gives an extreme example in this picture:
This is my *******ized attempt at one (I'm the old fart on the right). My youngest daughter is using a more traditional western approach with our Appy: