Yes, the sentences have two different meanings. "Get out of there!" is a command directed at 'you'. It means "Get yourself out of there!" While "Get it out of there!" is a command for you to remove something.

Being American, I am inclined to agree with Gary's answer. However, I think it is an American/British English difference. http://www15.uta.fi/FAST/US1/REF/engtran.html

It might also be confusing because in everyday language 'that' is often used instead of 'which' or 'who' which may not be correct, but it is common.

Almost. I would write the entire word, 'undergraduate' unless you were texting or writing an email to a friend. In informal speech you can certainly say, "undergrad". Make sure to say, 'UNDERgrad' and not 'UNgrad".

Both of those sound beautifully natural. They are both commonly used by native English speakers from America.

Hi Laèrcio, I hope you are well and that you are doing something fun this weekend. If you are asking about specific plans for Saturday and Sunday and today is Monday, Tuesday, Wednesday, Thursday or Friday, say: "What are your plans for the weekend?" or "What are you doing this weekend?" If you are asking about what someone regularly does on the weekend, say: "On the weekends, I spend time with my friends." or "What do you do on the weekends?" I hope that is helpful.

I understand that you want your wording to be more uniform. May I ask you to give more information about what you want to communicate? Are you trying to use different words to say similar things about your skills? For example do you have knowledge, are skilled in, are familiar with, and have experience in all these things? Will you describe your experience and level of expertise more? That would help me give you words and phrases to make a good impression. A little bit of information of what kind of position or job you are looking for would be helpful too.

Gracias Gloria, this was very helpful.