No. There is no such thing as a flawless program, so don't aim for that.
What you should aim for in for a first release is good/thorough documentation, some automated tests, one or more places for people to tell you about any problems they have or features they'd like to see, and a clear/prominent description of what your program library is and is not supposed to accomplish. And it should actually work, obviously.
Regarding reputation, I would expect people to care more about how you respond to bug reports/feature requests and how your program evolves rather than how pristine it might be at version 1.0. If you have at least the things I mentioned above, you'll be in a good position to respond well to all the input you'll inevitably get.
Reusing code from another app is fine if the license allowed it and you follow all the license terms. I would also try to attribute it somewhere even the license doesn't require it; that's just more polite.