MIPS Main Control Logic
If the hardware defined in your datapath supports the new instructions without adding any new control signals, then yes, just go ahead and extend the table to the right!

Augmented answer per augmented question:

The answer depends entirely on the datapath and what your control signals mean... I presume the ALUOp bits are each respectively the select signal for a 2x1 MUX, each of which in turn selects the operand inputs to your ALU. In that way they can be used to select either a value from a register or the immediate from the instruction itself. So for immediate instructions, you are probably going to choose the "register" input for operand 1 and the "immediate" inupt for operand 2...