Modbus and Bacnet Main/Sub

Using a T3-BB, can I use Bacnet on RS485 Main and ModBus on the RS485 Sub at the same time ?

Also, if my T3-BB is Modbus Master, and my T10 are all slave in a daisy chain, does I need to put a termination at the end?

Definitely, the T3 series controllers support two RS485 subnets, you can set the protocol and baud rate in the communications settings dialog. One can be bacnet and one can be modbus. You can write a program which reads & writes both subnetworks over the two protocols.