I would like to sell desktop software online, but I have very limited resources and can't always give 100% support to the customers.
I am worried about how customers might react to poor support and buggy software.?The business will be a shoestring operation, so I can't be sure if I can refund the customer and fix all bugs immediately.
tl;dr what is the easiest, hands free, risk free way to sell software online?
I've been in your situation (i.e. selling software on-line and not having much time to do so since I also had full-time job).
There is no answer to your question. There is no secret way that allows you to avoid all work and avoid refunds (just like there is no secret way to write complex software quickly).
Instead, a few thoughts based on my experiences.
1) Don't ship buggy software that requires lots of support.
Only a tiny minority of users ever asks for support, so once support load becomes overwhelming, you should already be very rich due to all the customers who paid for your product.
To give you an example: my SumatraPDF gets 20 thousand daily (~500 thousand monthly) downloads and there's barely a few posts a day on my forums (questions, bug reports, feature requests etc.).
If you manage to sell 1 thousand copies a month at $10 copy you'll be able to quit your job and focus on this business full-time.
In decent software support is not a problem.
2) Always refund, no questions asked.
Only a tiny minority of users asks for refunds. If you get an unusually high rate of refund requests, there's something wrong with your software (you either misrepresented what it does or it's extremely buggy).
3) Instead of avoiding talking to customers do the opposite: solicit feedback in any way you can.
You seem to think that once you release your software there will be flood of customers, each of them eager to talk to you.
The reality is: at first, you'll be lucky if you get a few downloads a day and no one will bother to ask you questions or give feedback.
The way to be successful in software is to build software that does what people want. You won't know what people want if you refuse to talk to them.
An hour spent communicating with your users can save you weeks of coding time (implementing a feature that no-one cares about) or give you ideas for features that will make your software more desirable.
In software business you should be begging people to give you feedback not avoid it.
4) Automate support as much as possible.
Have a forum, so that maybe people can help each other, without your involvement (although you also should be answering question promptly in the forum).
When the same question comes up multiple times, either fix your software so that it's not confusing or add an answer to a knowledge base on your website and point people to that page.