Can yoga help? Certainly! Can yin yoga help you? Yes, but...
You have described many physical challenges that you have right now, and these are to be respected. Before embarking on a yogic journey, I would suggest you clearly think through your intention; are you wanting to get healthy, or are you seeking high performance?
I am going to assume the answer is, health. Even if you are seeking high performance, you will want to regain your health first anyway. (The question in the back of my mind is, did your practice in martial arts contribute to your current physical challenges? If so, perhaps you were too focused on performance in the past at the expense of health. I will leave it to you to mull that over.)
Yin Yoga can assist in strengthening the connective tissues that were damaged in your operation and by other prior activities. You can read a lot about how to use Yin Yoga and its benefits here in this web site, but also your idea to read Paul's book is good too. Just be aware that before you start to work on greater range of motion, first let your current injuries heal. Focus on stimulating and mobilizing gently these areas. Don't go to far too quickly.
Yang yoga is also a big plus at this time too: again, go gently. The intention is to strengthen the muscles that will support your joints. Your intuition about NOT doing power yoga right now is a good one. Stick to gentler hatha classes or even restorative classes until you are pain free. Then slowly work towards the more challenging classes. Strengthen the leg muscles around the knee with standing poses, chair poses and gentle stretches like Saddle (perhaps just one leg at a time.)
There are several other posts in this forum about the knees that may help.
The best advice: talk to a teacher. Explain to her the challenges you have and see if she can give you specific instructions for your knees and watch you as do the poses. (It is difficult to do this via the internet - best to get someone to watch you!)