'Get' has MANY definitions.Examples are: He will get (arrive) home late, Can you get (fetch) me a spoon? I will get (an effect) my hair cut.
'Obtain' is a synonym (two words meaning the same thing) for one of the definitions of 'get'. Obtain means something has come into your possession (it is now yours). Example: I obtained the ability to read once I learned the alphabet. I obtained more money after getting a job
This one is a little trickier and will just take practice. 'To' also has many many definitions and functions. A few examples are: I walked to the store, It is five minutes to 10 o'clock. I am five miles to the east of you.
Some examples of the word 'For' are: I sing for the fun of it. This flower is for you. I dance for the applause.
Here is an example where you might need help distinguishing the two. "It is important for/to me to learn English." In this case, if it is important "for" me to learn English, that means there is a meaning behind me learning English. For instance, "It is important for me to learn English so I can talk to my friend in England." If you were to say "It is important 'to' me to learn English," It means that you value learning English.
Lucky for you, there's not big difference between 'talk' and 'converse' The main thing I can think of is the amount of people talking. One person can talk, a million people can talk two people can talk to each other,and any number of people you can think of can talk. It doesn't matter the amount of people, you can always use the word 'talk'. 'Converse' refers to the word 'conversation' which is when two (or more) people are talking to each other.
Example: If a professor is giving a lecture to students, the professor is talking. They are not conversing because the students are just listening. However, when the professor has lunch with another professor and they both talk about how their day is going, they are conversing.
Whew! I really hope this helped! :)