Archiving and Trimming Various Logs

There are various logs and messages BF keeps in the underlying RDBMS. I know it is possible to change length of time these are kept etc.

However, I have a question that crops at some large corporations where some data needs to be kept for 6 year or forever. They want to be able to trim the online size. For example going System->Messages crashes BF if there are too many messages.

1. Is it possible to dump out System->Messages to somewhere for archiving?
2. Is it possible to dump out build logs for archiving? Yes I know there are the build directories that may need archiving as well.
3. Are there other logs?

It should also be possible to "trim" the logs manually. Currently BF "automatically" trims on a rolling basis messages if various options are set.

Trimming of build logs is also automatic on a rolling basis based on productt class.

There are really quite a few questions here. One is managing System Messages which arguably is one of the more challenging pieces of the tool. There is an automatic cleaner as you have alluded to, and there as well is an export tool which can be used to store the messages in an offline system. This tool is bfmessages.
Usage: bfmessages

-l lang_spec Language in which to display messages, e.g., en_US
-p #:# Paginates from line number to line number

This will allow for exporting of the messages. Unfortunately it is not done by time stamp, rather page numbers.

For the second piece - there is a tool for this as well you may wish to investigate. The bfbomexport tool has had log\BOM export tool as well which can be used for this purpose - bfbomexport.
Usage: bfbomexport

options :
-f : file to write the output to.
-p : project Id of the build. -p or -P must be specified.
-P : project Name of the build.
-b : build Id to export the BOM of. -b or -t must be specified.
-t : build tag to export the BOM of.
-L : include Step logs.
-h : this help message.