Ye definitely checkout the laracasts learning from scratch series as @36864 suggested. Its easy to follow and if you do get stuck pop on the forums and you'll get some friendly help :) ....
Sure you can. I am not aware of any video guides for learning laravel 5.6, but it's entirely possible to learn how to use it only from the documentation.
Check the upgrade guides for 5.5 and 5.6 to learn the differences between 5.4 and 5.5, and between 5.5 and 5.6.