Replication only for INSERT statements

Hi all,
I've got my first job about sql replication... I've read a lot around but I'm still in trouble
First I'll explaine my architecture:
I've got two db caching data directly from the field in realtime. Each one read data from different devices and they write on a table with an identical schema. DB must have a seven days cache flushing every night (this is very simple).
I've to make a replication of this data in a third db (historical archive) that should be updated every 5 minutes. There is also a fourth db that should be mirrored with the third....
DBs are on different servers (OS windows server 2003) and they are all sql server 2005
for third/forth i think to put a DATABASE MIRRORING in High Protection Operating Mode...
for replication from first/second to the PRINCIPAL I've think about log-shipping...
two questions:
does log-shipping can work only for INSERT statement?? I've to mask the DELETE operations need to have a seven days cache
which are the limitations of DATABASE MIRRORING without a Witness Server and in FULL SAFETY mode??

1. Log shipping is all transactions not for limited insert or delete ect... you can't filter...
If you want to do only insert then use transactional replication.
http://www.informit.com/articles/article.aspx?p=601350
2. Database mirroring: Without witness you can't set to FULL SAFETY mode...
Database Mirroring in SQL Server 2005
http://www.microsoft.com/technet/prodtechnol/sql/2005/dbmirror.mspx
Database Mirroring FAQ
http://www.microsoft.com/technet/prodtechnol/sql/2005/dbmirfaq.mspx

thank you very much!
lst question... do you know what happen if I configure two witness in my mirror configuration?