Need someone to help me understand a problem - engineering & stats

I'm interested in knowing how bond length, bond width, bond thickness, and the type of
adhesive affect bond strength work for a given specific data set (provided later).

Need help to determine:
- minimum number of experiments to be conducted (ie. DOF-1)
- N = 1 + (L-1)Pd (Pd - design parameters) & (L - levels)
- prepare an L9(3^4) orthogonal array table for design of experiments
- Signal to noise ratio (SNR)
nominal, larger, & smaller ratios (provided later)

Results already conducted (will provide later)

-Rank design parameters according to their "influence" on the bond strength
- using SNR (from greatest/worst influence on bond strength)

- Determine % contribution of each design parameter
- Percentatge contribution required SSk = sum of squares of the kth parameter and SST = sum of squares of all parameters

- Plot effect of each design parameter and dtermine optimal combination
-plotting mean SNR each design paramter at different levels.

Further information available on request.