I'll see if I can't help ya out a little bit here. This part is going to sound kinda vague but you should water..... as needed. In other words don't let it get too dry but don't let it stay soggy either. The chopstick/skewer method is a good, tried and true, practice. Insert a chopstick or bamboo skewer into the soil near the edge of the container and let sit for a few minutes, when you pull it out and it's dry it's time to water, if it's moist you can probably go another day or two. Don't try to set a schedule for watering but check to see if it needs it. Another good practice is for the first few times that you water pick up the pot before and after watering. In a short amount of time you should be able to tell just by the weight of the pot. When you water make sure it gets a good soaking (runs out the drainage holes), let it sit for, say, a half hour and then hit it again. This ensures that the water distributes evenly throughout the soil and doesn't leave any dry spots. Frequency of watering will depend on several different factors i.e. inside or outside, hot climate or cool climate, large deep pot or smaller shallower pot, etc. If this is your first bonsai you've made a good choice, Ficuses are well known to be fairly tolerant of a wee bit of over/underwatering. With a little time you'll be able to pick up on it's needs.
As for fertilizing, I would wait at least a month before doing any fertilizing. Over fertilizing can be really bad (mmkay?). If you just got the tree who knows if it wasn't fertilized right before you got it. So waiting a month will make sure it doesn't get over fertilized and will also give it time to settle into it's new home (everybody needs a little adjustment period eh). After that, and this is just my personal philosophy, go light. I use a very weak (4-4-4) liquid fertilizer that calls for 2 tablespoons per gallon of water and to fertilize every 2 weeks. I use about a tablespoon and a half per gallon and fertilize about every two and a half to every three weeks. Play it safe. I've said many times before and I'll say it again, 'under-fertilize and it may not grow as vigorously as you would like, over-fertilize and you get a dead tree'. Simple.
Another thing you may want to consider, after it's had time to settle in, is some pruning or even defoliation. Your tree looks to have some really dense foliage and I'm a little concerned you may see some leaves dying off in towards the center due to lack of light. You could possibly prune out the center and head that off, thus leaving the tree to concentrate it's energy towards the outer parts or prune the outside branches so that more light gets to the leaves in the center. Either/or, tis only a suggestion.
Look for 'Zootenval's' post labeled 'Ficus defoliation' for a really excellent example of how to go about that. May not be something you want to try just yet though. Hope some of this helps and good luck.
Happy little trees!