i want to setup a vps to host my web site / application using existing firebird databases

1- after some search , it seems that the recommended linux distribution for a web server is centos 7, then ubuntu .

any feedbacks , recommendations, ideas on this please , and how it behave with firebird ?

2 - i am not really  a linux user , what is the best place/directory  to put the fdb databases ?

3 - i have several databases for differents custumers (20 / 30 or more), can a single firebird server handle many databases correctly ?

thanks .