These are the few things I’ve learnt:

The pea packet says to sow in damp soil and then not to water again until they sprout.
Beetroot and silverbeet seeds are soaked to promote germination.
Carrot seeds should be kept moist until they sprout.

What other ‘rules’ are for various veg when it comes to handling seeds (particularly interested in water, not to water, etc)?

as a rule of thumb large seeds like legumes can hold enough water until germination and can rot if they get too wet, while small seeds like carrots can dry out before they germinate so need to be kept moist. Soaking seeds beforehand I consider optional but may improve germination time and rate.

veges are grouped together because they are approximately the same in their water requirements. there is some advantage to planting them all together at once, in that they have different requirements when young. basically they all need at least a cupful of water each day to get them established. once they have their root systems working (say 4 weeks after planting) you can switch to less frequent waterings (say twice a week).
some points of interest
- you are force feeding veges – so max. food and water is the rule.
- you need soil that is free draining AND moisture retentive (organics).
- they respond differently to overhead watering – some like humidity.