4-5; there are just so many amazing artists here on dA, it's very humbling. When I just draw on my own and look at my work, I think it's fine, but when I log into dA and look at others' work.. I don't know if it makes me feel awful about myself or inspired, haha.
I said 6-7 because no matter how "good" you think you are there is always someone out there who is a bit better, it should hopefully keep you striving to give your best. Art is hard to rate as most work falls into love it or hate it, ya never know whats going to excite the masses. You could be hot 2day and not tommorrow, lol.
Well, it's not that people who haven't studied art are automaticly worse or less then the ones who do. It's just a matter of practise, if you do it in school or at home doesn't really make a big difference, as far as i've noticed.
Digital stuff can be a bit rough at the beginning but if you spend enough time in it and develop a certain style it becomes easier