Answer 1

i think solo learn is the best way and you can gat more tutorial on you tube,and there are many websites like tutorial point ,w3schools etc

Answer 2

YOUTUBE, LYNDA ETC

Answer 3

maybe... i learned it by coding my own e-commerce system. Not for make money with it. only to understand the coding.

Answer 4

w3school udacity Khan academy

Answer 5

if one is looking for something in german language:
selfphp.de is a good starting point