Couchbase multi tenancy

Hello All

i have a Q if anyone ran into this before as we trying to figure few things out , we have our APIs running with couchbase and after testing we were able to fetch a Record within 20MS from 1M doc and all this with a single server and single bucket

my Qs as follows
1-for a single bucket how much can i hold in it Record wise
2- for multiple users what is the best way to do a cluster or a farm of DBs and buckets to connect and fetch

i am trying to find out if ever someone used this with Multiple users and each user has its own bucket or farm of nodes

any ideas

thank you