But assuming a building permit is granted, is it allowed to build with a priority notice of conveyance?
If the building permit is available, construction is allowed - regardless of who owns the property at that time. You only need to inform the owner or get their consent, but in principle, you can build on someone else's property, yes. Even without a priority notice of conveyance.
However, the priority notice of conveyance does not replace the owner's consent.
Much more important in this context would also be the relevant clause in the purchase contract regarding the transfer of rights, burdens, and obligations. This is presumably linked to a logical step in the implementation of the purchase contract, but it can also specify a certain date or a combination thereof.
And can a priority notice of conveyance be registered on a divided property before a continuation certificate is available?
Kind of. The priority notice of conveyance applies to the existing property, so in the case of a property yet to be divided, it applies to the entire original plot. If you acquire a partial area from that, the priority notice of conveyance is transferred to the portion that is the subject of the purchase contract after the division. The owner can logically do whatever they want with the other part.
If the other part is simultaneously contractually assured to another buyer before the division, the notary would, of course, see that there is a priority notice of conveyance for the entire plot - but based on the (map) attachments of the purchase contracts, they can determine whether the priority notice of conveyance for parcel A affects the purchase contract for parcel B or not.
So the priority notice of conveyance is initially just a warning signal for the (next) notary that there is another concurrent land registry process on the property that may need to be observed or waited for.
Regards
Dirk Grafe