Firstly as I am a Podiatrist and interested in mechanics of the lower limb, I can offer you my perspective and hopefully clear up a few misconceptions for you.
Permanent Orthoses- that's also a new one on me- I isuue off the shelf, semi custom and custom orthotics, so I think that your Podiatrist is referring to custom-the question for the prescribing podiatrist should be whether you are a long distance or sprinter- this will determine the type of custom orthotics you need. And yes you don't have to get orthotics actually. the advice given to you about going to a specialed running shop to assess your running gait is a good one. The staff there will be able to determine whether you need a running shoe with or without correction. If you go for one with correction then you may not need orthotics-it depends on how much correction is in the shoe. However from personal experience of corrective footwear and being quite a severe abnormal pronator ( and no over or abnormal pronation is not normal, but it is common- pronation is normal- too much is abnormal, and can definitely lead to torsion on the knees and stress on ligaments and cartilage-hence knee pain), I didn't find the correction enough to support my running style, but a pari of neutral shoes with orthotics I have found much more comfortable.
Also if you are using orthotics in your shoes only take out the inner sock if they are full length and in a neutral pair.
As to variance- in fact this is varus - it means that your feet are in an inverted position just prior to heel strike so that they have enough pronation available in your joints to get down to the ground.
Off the shel orthotics can be ok for a short period of time but remember they are stock orthotics not specifically designed to your feet where as custom ones are and are always going to be better and give you better correction and last longer.
Hope that helps, please feel free to ask me any advice.