Logical Standby from RAC to single instance

I had setup Physical Standby on Oracle 10g earlier but never on a RAC environment and not a logical standby

Here is what I have
2 node 10gR2 RAC on solaris 10 using 11g CRS & 11g ASM

I want to setup a single instance logical standby for the above RAC database.

Here are my questions regarding logical standby.

1. Is absolutely needed that every table in the database to have either a PK or UK?
2. when I use the RMAN to duplicate the target database for standby, in the init.ora of the standby do I have to say cluster_database=false and once I open the database do I drop second thread and second undo tablespace?

I googled for pointers but could not get a lot of help. There is a MAA paper about standby RAC for a Primary RAC.

Can any one point to a step by step process.

Any help is appreciated.

thanks
deen

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