פיאות

I always found this topic to be mysterious and unexplained, so let's see if we can make heads of this.

a) the nature of the prohibition is not to make the hair "rounded". it would seem from that, that if one leave even "some hair" he isn't transgressing the isuur. i found that this is a discussion and there is an opinion that holds this way.
b) the length of the פאה is a dispute amongst the rishonim. the language of the שלחן ערוך is:
שיעור הפאה מכנגד שער שעל פדחתו ועד למטה מן האוזן מקום שהלחי התחתון יוצא ומתפרד שם וכל רוחב מקום זה לא תגע בו יד
there seem to be many opinions how to interpret these words (which are quoted in Biur Hakacha 251). There are those that say he means until the end of the ear, meaning at least till the beginning of the אליה (the soft skin at the end of the ear). In my humble opinion, it sounds more like those who interpret to be the middle of the ear, where the 2 jaws connect and he means till the end of the top jaw and before the beginning of the bottom jaw. to feel this, open your jaw really wide (preferably when no one is watching) and put your finger at the junction. According to this "למטה מן האוזן" would mean, under the hearing canal.
c) the width of the פאה (a.k.a - the "boot"). another thing i never got was, how far into the face - width wise- is one not allowed to shave. you see people having 60's type boots, so what's with that?
perhaps, it also is connected to the junction of the 2 jaws, and when the law states וכל רוחב מקום זה לא תגע בו יד he is referring back to the junction and is describing the width not the length (as some people understand). in which case, i refer you to the diagram of the skull @ http://www.besthealth.com/besthealth/bodyguide/reftext/images/CranialBones.jpg
you will see that the bone structure of the junction of the 2 jaws end right above the beginning of the back teeth. so in my opinion, this is how far into the face one needs to go.
d) finally, and perhaps most importantly, what are or aren't you allowed to do in the place of the פאה?
We are מחמיר not to even use מספריים כעין תער like our tosfos says. see my comment on the shavers post, where i quoted the כתב סופר that you aren't allowed to cut the hair even with scissors if its very close to the face (unlike by the beard which it is allowed), and מעיקר הדין all you need to grow is "something" of hair, but the minhag is to grow each hair to be long enough to be able to fold. i will not go into other minhagim of peos (although i was surprised to find that some are AGAINST very long peos from a kabalystic point of view). So if you ever see a guy with a completely shaved (with a trimmer) head, know that he is "only" transgressing a minhag...

would love to hear comments on this.