Is Khan academy pre-cal enough?

I suggest you doing all the Precalculus section (100 %) and then moving on to a textbook. Don't stop learning. I haven't seen the material but Precalculus is a broad course. I suggest you after doing the 100 % on KA course to do all the OpenStax book from Rice University. You can find it free on the internet. Whenever I continue with it I can hit you up and do a hardcore study session. I'm planning on doing that but I'm reviewing past math still. Hope to finish soon.  

My suggestion would be that you first absolutely finish the course here. This way, even if not all of it is covered, you will be familiar with the basic topics. From my experience, I know that even if Khan Academy might miss a thing or two, they always cover up the topics that are major and built the understanding of the course and that's what you need first, a solid understanding of the basics. After that, I recommended you can get the textbook and look through the topics listed in that. If the course covers up everything, then great, but if it doesn't then look through the stuff and see whether if you can understand it or not. If some of it you don't get, no worries. You can always, always find something on the internet that can help you out. There are many fascinating math teachers on youtube that have amazing knowledge. Try this out and then tell me if it worked. 

Hope it helped