nchar and nvarchar columns will have no problems storing these characters. However storing could be a problem. This will affect you if you have any clustered indexes set up on any of these characters. You will probably want to set the collation for the database/table to the most frequently used sorting order.
For queries much depends on whether you need to sort based on these columns. Same collation rules apply. Query tuning can get a bit painful if you have to connect tables with different collation orders.
Andras
Andras Belokosztolszki, MCPD, PhD
GoldenGate Software