Outer Joins in Multi Source Universes and ANSI92 Parameter

I am writing this thread to ask some questions about outer joins created within multi source universes (based on JCO connections) on BW cubes.  

1. Will Outer join within a multi-source universe work even if the universe parameter ANSI92 is set to ‘No’ or the ‘ANSI92’ is not even in the parameter list.
2. I have seen some behavior regarding outer joins in MS universes where an outer join behaves as an inner join.  Is it because of the prompts set in the webi report inserting a where clause in the SQL generated at run time or is there another explanation.  I have seen an oos note (1834782)that talks about it.
3. Lastly, is there a consensus as to which join is more efficient, outer join or inner join?