Purchase order suggestions

SP10 has fixed the rounding problems on purchase orders which is great. Now that I can use purchase orders I was wondering if the following PO features were on the road map:
1) Ability to use our own PO numbering system
2) Ability to enter historical PO's (I get an error if the required by date is less than the current date)
3) Additional Sales Tax fields (in Ontario, Canada we need to show GST and PST as separate line items)
4) Sort the vendor dropdown (I would suggest that most if not all dropdowns in SD need to be sorted)
5) A very minor display issue, the labels "created date", "required by" and "status" are not aligned the same.

Thanks!