1) Understand I you correctly, you want to enter the password once when you log in application Qlik Sense? If so, it all depends on which option Qlik Sense you are using.
Option 1 - using Qlik Sense Desktop/Qlik Sense Cloud. The logins and passwords will have to be entered twice in any case, even if they coincide - when entering the cloud and when entering the application.
Option 2 - using Qlik Sense in jointly with QMC (Qlik Management Console). If you have a domain account organization, you can configure it so that to open your application Qlik Sense you need to type the password once. Otherwise (without a LAN domain), you will need to enter your login and password twice, as in the first variant. On this issue, you better communicate with your system administrator of your local network.
2) To date,not ability to upload data to the cloud application Qlik Sense using OLE DB connection from SQL server.