Is it rude to send my professor a link with teaching advice?

To show that you're an independent learner, I'd suggest don't just send the link, but read the materials in the linked page and summarize them to your professor, tell her if you think it may be useful for the directed studies. For instance, instead of:

And here a link (URL) provided by the text on how to teach this book.

Try:

I also found a link for teacher and read up a bit (URL). I think the suggested chapter sectioning for a 7-week syllabus seems suitable to our directed study time frame, please let me know your thought.

Or something along the line. I think you're quite lucky that the professor was being so up front about her lack of background knowledge, it should be a good directed study experience. But in turn, you'll need to bear some of the self-teaching responsibility, and don't expect that she can read some pages about how to teach the subject and then magically be able to teach you.

Yes, it is (very, IMHO) rude, and yes, it is exactly as bad as the title makes it sound. I am sympathetic to your concern that your professor may not end up doing the best job she could due to not being aware of good advice. Nonetheless, it is not your place to tell her how to do her job, and sending her a link with teaching advice falls into that category.

At the same time, it is your place, and well within your rights, to communicate to your professor your needs as a student, so it would be perfectly appropriate to send her an email and let her know about any action she could do that would be helpful to you as a student (I mean an action that is directly related to the course and how she teaches it, not an action like "study the material of topic X so that you know it better"). But as I said, PLEASE do not send her a link with teaching advice.

Also, if during the course you find that the professor is doing an especially bad job and does not address any requests you made of her to teach in a more effective manner, it would also be appropriate to complain to her department chair or other superior. But I would reserve such a measure for truly extreme circumstances.

It would be less problematic if you mentioned it in passing (in person).

Something like "How's it going planning the class?" and then "Did you see the tips for teaching this class? I think all textbooks should have this!"