Here is my opinion on the questions:
1) It is not necessary to include a requirement (nor a precondition) for a supplier to have a Tax Clearance Certificate (TCC) before they are registered on the supplier database. It is however a requirement that the organisation should be in position of a TCC (original and valid) at the time the price quotation or bid response is submitted/received. From a practical point of view, it is practical for both parties to include the TCC in the database registration process, however it is not a precondition for "registration". From my standpoint, there are two reasons for this:
1.1) In all the TCC references in the PFMA and the SBD/MBD's the terminology refers to the condition that a contract should not be "awarded" if the supplier's tax is not in order. The reason (in my view) why there is a requirements to have the TCC submitted or in hand only at the time the quotation/bid is received, is because that is the point when the project/job contracting process is deemed to start. The process for registration is not a contract between the state and the supplier, but merely a practical initial step for fast-tracking the quotation and bidding and contracting process which may (or may not) take place at a later stage.
1.2) Suppliers should be on the Register in order to be considered for price quotations below R30,000 (for the same "fast-tracking" reason) even if they have not submitted a valid original TCC. If they are denied the opportunity to register because they do not have a TCC they could argue that they are being denied the opportunity to submit quotations (if less than R30,000).
(In my experience, many organisations do not have the correct wording on paperwork, standard bid documents and processes to support the checking of TCCs that have been submitted by supplier's on earlier bids/quotations)
2) In terms of the threshold point, my opinion is that a valid original TCC is only required for bids/quotations above R30,000 (including VAT).
ShaunCScott