Bull Rushing multiple questions?

[Noldor Elf]

Following situation:
_ _ W_ _ W = wizard
_ _ _ _ _ F = fighter
_ _ F _ _ D = druid (wildshaped as Brown Bear)
_ _ _ _ _ Each line is 5 feet.
_ _ D_ _

The Druid Bull rushes fighter. On average rolls he (STR +8, +4 for beign large = +12) beats fighter (STR +4) with 8 points.
If he chooses to move with the fighter he would push fighter backwards 5 feet + 8 feets = 13 feets.
What would happen when they reach the square where wizard is standing?

Additional question:
What's DC of consentration check caused by bull rush?

 

[dcollins]

In this case, I simply apply the rule at the end of "Bull Rush Results" on PH p. 137 to the fighter. "If that space is occupied, you fall prone in that space."

Second question: DM's call. I suggest equivalence of "Violent motion" (PH p. 65: DC 15 + spell level).

 

[Noldor Elf]

What if the attacker have change to push taget further than the occupied square? Should him be able to take that other "target" with him also?

 

[dcollins]

DM's call. No definitive rules exist.

(You may wish to ask this question on the "DM Stuff" board, which invites house-rule commentary.)