Solo 401k and its effect on w2, 1120S and 941

I have a S corp. For example my total wages are $48000 on which I pay social security and Medicare
I have contributed (through my S corp):
$ 30,000 - Elective deferral Solo 401K, of which
$ 12,000 - is employee contribution (profit sharing) and
$ 18,000 - is the Employer contribution (elective deferral).

How would my W2 reflect above contribution apart from entry on 12 D.?
My questions for the pros for W2 form are-
1. What should be the amount on Box 1
2. What should be the amounts on Box 3 and 5
3. What should be the amount on Box 12 D

Questions about 1120 S form
4. Line 17 is for the profit sharing plans etc… so should It show $12000?
5. What should be on Line 8 which is for salaries & wages, Should this amount be $30000

6. What should we report on Forms 941/940 related to solo 401K?
   As per above example, do we report 30,000 on Form 941 Line 2, & 48,000 on Form 941 5a, 5c?
 
Please help in the above situation.