IS 'Where' used as a pronoun in relative clauses?

1.(a)Statement.......:He works in a office.
...(b)Relative clause:1.The office where he works.
... 2.The office in which he works.
Here,'where =in which'. and I think 'Where' is used as an adverb to mean 'in,on,at or to which' in relative clauses.

2.(a)Statement...... :He works near the office.
(b)Relative clause:The office near where he works.
I think here 'where=the office'.

My questions,
1.Is 'where' used as a pronoun? (as 2.(b) )
2.Can we us other prepositions of places (except 'in,on,at,to') with 'where' as 2.(b)?
e.g: 1.The bridge under where we live.
2.The Beach behind where i am standing.
3.The shop next to(close to/before/opposite/in front of..etc..) where we live.