Good to hear. Yes, first plantings can be a trial by fire.
To water the plants you could just "read" them, where the plants will start to wilt subtly when they're thirsty. You look at them enough, and it will be obvious. That's the best way. You could also stick your finger in the soil, and ideally find it moist an inch or two down. Don't go by frequency. The frequency depends on temperature, humidity, sunlight, and even soil structure.
Onions multiply? Nope, one plant makes one bulb. Be aware that the bulbs don't even start to form until the last month or so before harvest. So don't gaze longingly at the plants, hoping to see little bulbs getting bigger and bigger throughout the lifetime of the plant. They don't do that.
Support peas? Peas have tentacles that will want to grab onto things. They climb. Give them things to grab onto. Sticks, strings, netting, mesh.
