Just my two cents on the AutoInc field -- I don't use it either.

I have a routine that autoincrements using 0-Z (zero through letter Z). This gives 36 digits (Base 36) in each byte position (instead of ten). The field is a char field and I left pad the field with zeros (built into the autoincrement routine). This gives a much higher number of combinations in a smaller field; for a 5 byte field, a base 10 gives 99999 unique values, whereas, the base 36 gives 60,466,176 unique values (36**5 combinations).