Re: v-score depth on pcb
I always requested a minimum web of 0.5mm on 1.6mm boards, and a groove angle of not more than 45 degrees. Ref IPC-2222A page 16. For a 0.8mm board I would suggest some experimentation, to small a web and the panel becomes unstable to handle, to much web and the cutter can wander during de-panelisation.
That said there are some points to consider with v-scoring:
It is one of the most stressful ways to de-panelise PCB's, be careful of MLCC caps near score lines and other components sensitive to bending and stress, even if you are using a cutter. The automatic in line cutters are better than manual ones.
With V-scoring you have to plan your panel out carefully, as it is very easy to make a panel that will sag during the thermal cycles, hense I never had a web less than 0.5mm. You need to know what heat cycles your board is going through: Reflow, 2 side SMD, Wave, Selective Solder. At 0.8mm I presume there are no heavy components, as weight distribution on the panel is important.
I'm not a big fab of v-scoring, but have used it quite extensively in a high volume production.