Multi-DB compatibility questions

Hey,

I had a few questions with Multi-DB install.

1). I read Multi-DB is not compatible with W3TC. Is Multi-DB compatible with DB-Cache or any other Database caching plugin/mechanism ??

2). Is there a way to disable the W3TC database caching mechanism & hence avoid using the db.php file …so that it doesnt interfere with Multi-DB ?? I know this shud go to W3TC forums….but just wanted to know if someone has already looked into it.

3). Though I am planning to go with a 256 DB install, I wanted to know if there is any performance loss (or gain); if I go with a 4096 DB install on a very new website with only 10 blogs. I plan to scale it going further to 1000’s of sites, so i decided to go with multi-db.

4). Does “Multi-Network” (not multi-site) play well with Multi-DB, Pro Sites & Membership ??

5). I see I cannot use object caching, db-caching, minify, css sprites features coz Im using Multi-DB ….is it worth going for Multi-DB then ??

6). All Buddypress tables go to the global database…is there a way to shard the global DB itself if the global DB becomes too large ?? What i mean is…can I have multiple global DB’s ?

7). Do you’l know of any good query optimization techniques ??

8). Any other Plugins available either thru WPMUDEV or elsewhere which wil help in my setup ??

9). Any script or WPMUDEV plugins for easy multi–db backup ?

Thanks Guys !!

– Harry