[dba-SQLServer] Tables in Other Databases

Access XP ADE, SQL2000.

I have two databases that are identical in table structure.  Some of the 
tables also have identical data in them.  I am in the process of changing 
the sprocs so that the identical data tables are only included in one 
database and both databases use these (so that the data only needs to be 
updated in one place).  Updating of data in these identical tables needs to 
be able to be done from either front end.

I understand that to reference the tables in the first database from the 
second one all I need to do is prefix the table name with the database name 
(eg database1.dbo.table).

Q1. Is there any way to ensure referential integrity is maintained between 
the two databases?  If not, is the only solution to prevent deletions so 
that there is no risk of orphaned records in the second database?

Q2. Are there any other things I should be aware of with this arrangement?