Well, it looks and sounds like you're doing pretty well so far. It's not a bad idea to bag your promo spaces early, but I'd advise not putting too much work into promo during pre-production. Focus most of your effort on making pages, and don't tip your hand too early by showing all the good content before release; you need there to be some freshness and surprises when you actually release. Release some bits and bobs to build hype and a fanbase, and to help keep yourself motivated, but try not to overdo it. Leave some big juicy stuff for launch week! 
With regards for aiming for publishing, this art looks very polished, so it's not out of the question. Generally publishers won't show interest until you have at least 10 pages of sequentials as a sample plus script for about 50 as a minimum, so try to rein in your enthusiasm a bit, BUT there is one thing you can do to "future proof" at this stage for publication, which is always making sure you have print resolution 300dpi versions of your files (typically should be in the region of 1500 pixels wide). Making sure you have high resolution art files from the start means you'll have options down the line if you want to go to print.
So basically for now, focus on getting nice quality pages done that look good online but you also have print versions waiting in the wings, and try to build a fanbase by creating quality content on a regular release schedule.