H2 or MYSQL ? How to build task which reaches to 2 databases?

Hi,I am new to Bonita(community edition)

In my process I have a task  just reaches to DB and updates some rows or columns...and another task needs to reach 2 DBs to get data for calculate something...

my first question, when I have many DBs(4-7 /300rows in each one)with read and update operations what is the best :using external DB such MYSQl or using H2 DB? if H2 ,how I can use it to build DBs?

my second question,in this type of tasks is there needs to use business data variable with form and link it to the task  or just use connectors to DB?can I use  from one task 2 connectors to 2 DBs?how can do such tasks?how to connect to database from bonita studio?

thx