Hi, when you dont have many info on a model type, you can have a good CG estimative using a software like this one, https://www.ecalc.ch/cgcalc.php to start with.

About the flaps for landing, the quickest way to setup them is using about 45 degrees down on both, and then using the flight mode condition on the transmitter, with the flap switch as the activator. In the first flight, slow down the model at a reasonable height with the landing gear down, lower the flaps and then trim the model. The flight mode will store this trim setting anytime you use flaps.

After having some flights under your belt, you can play around with crow settings, wich in this type of model is very effective. Have fun!