Welcome to bonsai, I've been growing orchids and a few sub-tropical and tropical trees under lights year round for more than 40 years. It can be done, and done well. I also have grown bonsai outdoors, for 40+ years, and some of my subtropicals are outdoors in summer, indoors in winters.
Honestly, growing and watering techniques for indoor growing and outdoor growing are somewhat different, of course principals are the same in terms of what each species of plant needs to be healthy, but learning how to grow well under lights or on the windowsill won't help a lot with growing bonsai well outdoors. The main differences will be in watering.
The species you have, podocarpus, ficus and serissa are all quite do-able outdoors for summer and indoors for winter. The Ficus will do the best in Maryland done outdoors or summer, in for winter, but of the list, Ficus is the only one you can really do a good job with growing indoors year round. Providing enough light in winter is always a problem for indoor trees, but Ficus will do better than most.
About watering. in my experience, dribbling water into your pots from a watering can is bad. It works okay for houseplants in potting soil or peat moss because these media will wick water around to all parts of the pot. BUT as your bonsai develop, you will want to move them to a more granular, inert potting media. When you do the mix will not wick water very well, and dribbling in water from a watering can or wand will leave dry pockets in the pot, leading to root damage and eventually death. The ''proper way'' to water is to flood the pot with water, let it drain a minute or two and then flood again, let drain then return to the windowsill. You want every particle of media in the pot to get wet, then let the pot drain so it isn't dripping, then return it to the shelf.
With only a few plants on the windowsill, best is to walk them to the sink to water them. If you have 50 or so on the windowsill, dunking the plant in a bucket of water, then returning it to the windowsill is a bit quicker than walking each to the sink. When I went over 100 plants indoors to water I set up my light garden in a way where I could drain to a sewer (in the basement) so I could use a garden hose indoors. But with only 4 bonsai, you should take the time to walk them to the sink, water thoroughly, let drain, then return to the windowsill.
When to water is an art. best water meter is your index finger, better than any electronic device. Dig finger in at least a quarter inch or more below the surface, feel for moisture, if moist, watering can wait, if bone dry watering should have been the day before, if barely damp, the perfect time to water. Notice the weight of the pot, the heft will change as it goes from wet to dry. A few weeks of using your finger to check moisture will ''calibrate'' your sense of weight, or heft, of the pot. Soon you will know if it needs water just by its heft when you pick it up.
Good luck, and welcome aboard.
