You mentioned: 
We are a company doing surveys with different kind of questionnaires. There is a company in Mumbai (MySQL) specialized in Type 1 questionnaire and one in Peru (SQL-Server) specialized in Type 2. I also work with a CRM system as Salesforce and want to connect these data as well. I thought about getting all these data into one in-house database using ETL. 

Reply: Yes, you need to pull the required data (based on business rules defined by Analysts or management) from the respective sites, into a data-warehouse (in-house), then point your reports to it. Otherwise you would need to create a data-warehouse on each of those sites (a lot more work). The catch is how do you connect and get the data from those sites (Mumbai, Peru, etc.) daily ? There are many methods to do it, but each will depend on your skill and speed / latency of network connection.