As far as bigger images, are you scanning them in or shooting them with a camera? If you know a photographer with a good DSLR camera, ask him or her for help. I can't see technical issues here on this computer to comment on the technical side. I would actually kinda hate being a painter in the digital age as you folks need to be able to paint and in many cases take a great photograph of it in order to showcase your talent.
As far getting your art seen on FAA, it takes time, and you need to help in that regard. Print up business cards with your AW or Pixels site listed. Meet like minded artists at galleries. Send links out on social media. Put out fliers, anything you can think of to get your brand out there. On FAA, you can still hob knob with folks. Join groups, contests, comment on other folks work. Some will argue this does not do much, but anything that gets your name out there is a bonus in my book.
Case in point. Someone asked me if I had taken a photograph of a train they wanted and I had not. But I had seen someone else on FAA who had and I was able to put the two together.
