First of all there are a load of good threads on the subject of general strategy if you care to search.
The shadow compiled this quite comprehensive list of threads of interest.
thread with links to threads
To give some pointers on your posted strategy:
I'd skip all the hands you're limping with, sometimes skip AQ (rest of the time probably limp/fold/raise if in late position), and limp jj and tt.
As the blinds go up, you're more and more looking to blindsteal. You say with the big stack take no chances, that is not quite right. You want to be stealing when you have a good situation for it, which probably is way more often than you think. The same is essentially true for playing a smallstack. You want to be looking for folds, not calls almost always.
On postflop play I don't think I can add any sng-specific guidelines. Don't be too afraid of slowplaying though. There are definately situations without the nuts when it is correct to slowplay. You imply this in your description of your headsup play though.