Is it necessary that we mock up the designs onto the iphone?

no need it.

Hi! Thank you for the invitation to this job, I really had fun working with this one. I just submitted some of my designs. Would it be possible to get any feedback from you? I stuck to the black and white color scheme, which I'm assuming is what you would need for how your cases are designed (from the photo you uploaded). It looks similar to what I have to do when designing things that get foiled or have a spot UV.

Let me know if this is how you wanted it. Thanks in advance!

In what format do you need the design to be submitted??

hello, thanks for your invitation. i am really grateful for it and as every one else is saying, i am having great fun doing this job. hope you are also liking my designs. if you have noticed, i have included deep thoughts in my designs. hope you like it
i hope the designs are up to the mark of your standards. eagerly waiting for your reply
regards
gulshan

Any chance you could upload a version of the template EPS compatible with Adobe CS5?