preposition and inversion

Please help me

I)"Excuse me. Do you know where the bus terminal is?"
      "It is _____ the large police station."

1)opposite

2)opposed to

3)opposite with

4)opposite to

please explain to me why 1 is correct,how about 4,i think it

should have a preposition ''to'' after opposite

II)outside his house were playing two children on bicycles-->wrong

outside his house two children on biccles were playing-->right

,I don't understand why i can't use inversion in this case

III)1)She went to Helsinki to polish her Finnish up-->wrong

--->the correct answer is:''She went to Helsinki to polish up her Finnish''

2)My father was always ordering about my sister --->wrong

---->the correct answer is:''My father was always ordering my sister about''

please tell me the rule,where should i  put the subjects?

Thanks in advance

hello Pieanne,thankyou very much for your response

you've helped me to solve my problems,thankyou.

by the way: can you tell me more about inversion? for example: near my house lives an old man-->is this sentence correct? if it is,plz tell me why ''outside his house'' hasn't got inversion while ''near my house'' can have?

thanks in advance