What are the differences between "like" and "as"? I know that "like" it's used as a verb (gustar) but I'm not sure when can I use it as a comparative and when can I use "as" if both mean the same. I hope that my question is clear. Thanks!

When can I use "too" and when "also" to say: también ? I know that "too" also mean "demasiado" but I'm not sure when I use it to say: "también" and why couldn't I use instead "also". I hope my question is clear. Thanks

What is the difference between start and begin?