Answer 1

For JDBC, tuturialspoint.com has some great stuff there
As for Java, there are several good sources, but I'd have to go with two websites
For free Android course by none other than Google: Udacity.com
For paid courses made by highly qualified people in the field or just really knowledgeable of the subject: Udemy
Both are very good sources (I happen to be using both right now, a little more Udemy), but what's important is that you will gain a lot of valuable knowledge from learning from these sites. Good luck!