Answer from cs61c-ck (Allen Lee 16583554) for Question 1
No.  Although there are different types of formats like I, R, and J, MIPS instructions have unique bit patterns.  For example, in R-format, instructions take the bit pattern:
op rs rt rd shamt funct
and I-format instructions take this form:
op rs rt rd address
Even though the address in the I-type and shamt funct may be the same, the computer knows which format by having distinct values for the op field.  The machine only sees "1's" and "0's".  If the programmer wants two different instructions, they cannot have the same bit pattern because the computer can't tell the difference.