How can I make electrical connections over v-score line?

I’m designing a new PCB where I have a whack of connectors that have to line up with the metalwork. There are some problematic connectors. All 4 pins are round. I want to have the holes as small as possible while allowing for good solder adhesion over the full length of the pin. I’m looking for guidance on how much clearance around the component lead I should have in order to get good solder wetting and adhesion.

I have some PCBs that were wave soldered but the vias still remain open, they are not filled nor plugged form what I can see. I do not see any solder on the annular rings of the vias either. How do they go about doing so?

I am a junior electrical engineer and last week I have joined a product develpment project which involves SMT PCB. Would you like to share some general steps about designing PCB?