DarkStar: The inventory on a planet does change just about every turn. It isn't just luck, though; rates on average for an item can vary quite a bit from planet to planet. Look for planets with single digit prices to buy at, and higher selling prices to sell at.
Ships can help early on, as can Pirate Contracts early on (mentioned by Taz), which will greatly lessen pirate attacks, and also as Taz said, pirates can't steal money in the bank (one of its purposes aside from the interest) until you can build a defense. Of course, you can count this a risk of doing business, and save that money for quick ship upgrades and items. There are many paths and strategies you can use.
Yes, there is a bug on some systems with the Trader demo that can cause it not to switch res's back properly. I believe the full Version fixes this problem, and all of the other demos shouldn't have this problem.
Sales here on Shrapnel? Not sure, though i've gotten lots of e-mails and compliments from people here, so I assume interest at least is fairly high. I hope anyway.
I think there's just enough eye candy in the games to where people won't dismiss them outright because of POOR graphics at least, especially for the kind of price the Thunder Pack features. I've actually been complimented on the graphic design and look of the games a lot of times. I'ts true there no fancy 3D cut-scenes or anything like that, which IMHO, eats up disk space and most people end up skipping it after the first time viewing it.
And yep (especially on Shrapnel), gameplay is what really counts in the end.
Thanks for your thoughts! If you have any other gameplay questions, write me here or e-mail me and i'll be happy to help out.