As far as I know (V-grooving) is a board manufacturer thing; you *tell* them you want the outline grooved. Purely rectangular outlines only
Yep, that's how it's done. On one of the mechanical layers, place the pcb board outline plus where you want the V-grooving to be done. Be aware that the V-groove will take up approx 1.0 to 1.6mm (might vary a little for different manufacturers).
If you want an SMD solder paste screen, have the same manufacturer produce this along with your panels. This way, everything will match.
Advise the manufacturer of the largest panel size your SMD robot can handle (or your infra-red reflow oven if the panel size is smaller). Let the manufacturer then work out the most economical layout for you.
A couple of other things - advise the minimum panel border size that you can handle, any location holes that you might require along the panel edges (where you want them & the hole diameter) and any fiducial marks you might require along the panel edges.
Unless you have the full DipTrace version, you probably can't set up all the pcbs in the panel anyway - you will run over the pin limit!
If you are doing volume boards, DipTrace have on their website an ISO Accredited manufacturer in China that will accept your DipTrace files. The PCB prices are good, the quality is good & the solder paste screen cost is about $80 ............... so a saving of approx $200 to $300 on what you would pay an Australian manufacturer. The usual photo-plot costs for the artwork is about $75 ........... so again a several hundred dollar saving on what an Australian manufacturer would charge you.
To the original poster - whim me if you can't locate the details on the DipTrace site & I will look it up for you.
Hope this helps.