upgrading Squid 1.0.9

I am currently running Squid-1.0.9 on a Sparcstation with Solaris 2.4 for
about 80 users and I gather it would be a good idea to upgrade to a more
recent version, but two questions remain:

a) Which version should I choose right now? The Squid homepage mentions
1.1.17 as "current stable version" and 1.1.18 as "most recent version".
Also, as my machine has only 32 MB, should I consider the NOVM version?

b) How do I proceed for a smooth upgrade with the shortest possible
interruption of service for my users? Should I remove the entire old cache
before installing the new one?

Thanks in advance for any help.

-- 
Tilman Schmidt          E-Mail: Tilman.Schmidt@sema.de (office)
SEMA GROUP GmbH                 tilman@schmidt.bn.eunet.de (private)
Koeln, Germany