I can only answer the first question as I've not submitted anything myself either........
No! You are not out of your league at all! I AM most definitely out of that league but you are NOT! Go for it. Your work is beautiful.
I am not sure I can ever reach the levels of beauty and creativity I see on here and on the blogs of those of our group; I do think I often rush through most of my work. But then I see other's work and realize, maybe I just am an "average" crafter hence why I don't really try to submit anything.
I do look forward to hearing the answers to these questions though. Is it hard? Are there so many submissions its almost futile? It's one reason I've also never tried to get on a design team. I don't think I have what it takes but would LOVE to try!