Hey, all good questions, I’d suggest you leverage good resources out there – Microsoft TechNet, forums, etc. Here’re just quick thoughts:
1. I work in the team that builds Quest Recovery Manager for SharePoint (http://www.quest.com/sharepointrecovery), so I cannot really recommend any other product out there :-) Recovery Manager can leverage SQL database backups and granularly restore site collections, sites, document libraries, lists and even individual list items and docs from the full content db backup.

2. I would suggest a dedicated content db for such a large site collection. You don’t need the site collection backup in this case, just back up entire SQL database. Good blog post on the site and site collection capacity planning and sizing: http://www.sharepointjoel.com/Lists/Posts/Post.aspx?ID=187

Yes, it is absolutely possible to limit number of site collections in a content database. Check the database properties in SharePoint Central Administration.

3. The only built-in tool that allows item-level restore in WSS 3.0 is the Recycle Bin. It’s not a backup tool, deleted data resides in the same content database in the Recycle Bin for 30 days by default.

4. You can, but not sure want to. SharePoint is a collaborative platform in the first place, especially if you use WSS v3 not full blown MOSS. 2+ GB files in SQL database are probably going to cost more in maintenance than on a file share.

5. If you’re using MOSS – check out my older post at http://blog.sharepoint-recovery.com/2007/12/11/how-to-move-a-site-in-moss-2007-its-that-simple/

We also have a tool that helps there (both for WSS and MOSS), it’s currently in Beta at http://sharepointforall.com/media/p/98.aspx (Quest SharePoint Reorganization Wizard)

6. I am not really a search expert, but yes looks like Search Server 2008 Express could be one of the solutions.

Thanks for the questions, and hope I could clarify few things for you!

I’ve deployed WSS 3.0 in a farm ( 3 servers, intranet ). List below are some queries :

1) I need to find a solid backup and restore tool/ solution (built-in or third party) to cater for future expansion and able to recover the whole server farm more efficient and effective. Currently, we are using CA ARCServe (Agent for Microsoft SharePoint), i think not really a tool that we are expected … Any suggestion ? DocAve v5 ?

2) If a site collection more than 200 GB, is it possible to do backup and restore effciently by using stsadm tool ? What is the size limit for a particular site collection ?

2) Is it possible to assign one site collection to one database ?

3) How do to a granular or item-level backup and restore with WSS 3.0 built-in tool ?

4) Currently, i set the max. upload size to 2GB. Is it possible to store a file more than 2GB in WSS 3.0 site ? Any file size limitation?

5) How to move one subsite to another subsite ( within the same site collection ) and able to retain all settings of that particular subsite ?

6) Due to WSS 3.0 search limitation, i cannot create multiple site collection for different department/team. Is there a way to do cross site collection searching ? Integrate WSS 3.0 with search server 2008 express (for enterprise search as well …) ? Any suggestion ?

best regards,
liew