We would normally say, "Don't get pressured into ...". The first and third are wrong, but I'm not quite sure about the other two. It's just a weird way to say it.

You wouldn't say "I have got .." but if you wanted to use it in past tense saying "I have gotten ..", that would be okay. "I have five dollars." "I have gotten five dollars from you."

Learn to speak the language properly before you try to worry about grammar. You can also go off of other people. Where you naturally have a small pause, a comma would be added. Where there's a longer pause, a period goes. Basically a sentence is simply a statement or question, and then it's ended. When you continue that idea, you use a comma. But you don't want to add one for the end of the idea because then you end up with a run on sentence. Like they've said above. If you're not being graded on it, it's not something you really need to worry about too much. Most people who have English as their first language don't do it correctly, including myself at times and probably during this response. If I were to be graded on it, I would simply read over it and see what sounds right and what don't. That don't always work, but it does for a majority of it. If you want to be perfect at it, then you will have to learn the formulas and definitions of parts of sentences and words to keep everything correct. It's quite difficult, and not very important for most people. Good luck. :)

To have something covered means that you'll take care of it. Person 1: "We need to set up the ladder." Person 2: "I got it covered." Person 2 is saying he will set it up, and that Person 1 doesn't have to worry about it.