Text :: Index Memory Parameter For Oracle Text Indexes

I am on Oracle 11.2.0.3 on Linux and have implemented Oracle Text.I created Oracle Text indexes with default setting. However in an oracle white paper I read that the default setting may not be right. Here is the excerpt from the white paper by Roger Ford:URL....(Part of this white paper below....)Index Memory.                                  

As mentioned above, cached $I entries are flushed to disk each time the indexing memory is exhausted. The default index memory at installation is a mere 12MB, which is very low. Users can specify up to 50MB at index creation time, but this is still pretty low. This would be done by a CREATE INDEX statement something like: CREATE INDEX myindex ON mytable(mycol) INDEXTYPE IS ctxsys.context PARAMETERS ('index memory 50M');  Allow index memory settings above 50MB, the CTXSYS user must first increase the value of the MAX_INDEX_MEMORY parameter, like this:  begin ctx_ adm. set_ parameter('max_index_memory', '500M'); end;  The setting for index memory should never be so high as to cause paging, as this will have a serious effect on indexing speed. On smaller dedicated systems, it is sometimes advantageous to temporarily decrease the amount of memory consumed by the Oracle SGA (for example by decreasing DB_CACHE_SIZE and/or SHARED_POOL_SIZE) during the index creation process.

Once the index has been created, the SGA size can be increased again to improve query performance." (End here from the white paper excerpt)My question is:

1) To apply this procedure (ctx_adm.set_parameter) required me to login as CTXSYS user. Is that right? or can it be avoided and be done from the application schema? This user CTXSYS is locked by default and I had to unlock it. Is that ok to do in production?

2) What is the value that I should use for the max_index_memory should it be 500 mb - my SGA is 2 GB in Dev/ QA and 3GB in production. Also in the index creation what is the value I should set for index memory parameter  - I had left that at default but how should I change now? Should it be 50MB as shown in example above?

3) The white paper also refer to rebuilding an index at some interval like once in a month:   ALTER INDEX DR$index_name$X REBUILD ONLINE; We are on Oracle 11g and the white paper was written in 2003.