About 3000 ANs are diagnosed in the US every year. Given that ANs occur between the ages of 20 and 80, multiply 3000 by 60 and you have probably 180,000 people walking around with an unwanted companions in a population of 300,000,000 in the US. So, no, not very common and the odds of 4 people with ANs walking into one podiatrist's office in one day are astronomical enough to lead me to suspect that maybe your podiatrist was kidding you.
If he wasn't, you've got the makings of an AN support group right in your town.
Anyway, with regard to the plantar fasciitis, did your podiatrist show you how to tape up your feet?
I had plantar fasciitis starting about a year ago and I had to get the orthotics. But what helped me more was taping up my feet to relieve the inflammation. Did that for about 6-8 months till it cleared up. Now, when I start feeling some pain in the bottom of my foot, I tape it up for a few days and that takes care of it.
You can buy rolls of sports tape at Walmart pretty cheap.
There are quite a few variations of taping techniques. This is the one that I was using and it worked well for me:https://www.youtube.com/watch?v=pLqRwJjHkm0
For my balance issues I have been wearing clunky walking shoes that have wide soles and heels. Exercises that strengthen your legs and ankles will also help along with the usual vestibular rehab exercises.