I've never heard of liability for common, well known, software frameworks. As long as you don't plan to use some obscure language like, say, Miranda*, there shouldn't be an issue. I always pulled in what I needed as far as packages, as well.
I worked a few 1099 gigs with a consulting company and then
ripped off used their service agreements as an example. Often, the client would supply their own agreement and I would just change it as needed. No client ever denied a reasonable change re: deadlines, response times, vacation coverage, etc.
Add in an LLC and some decent E&O and you're good.
*
https://en.wikipedia.org/wiki/Miranda_(programming_language)