If 1) is false, then nothing about the real world is possible to know. So, it is better to simply *define* the real world via potential observations.
Yes, you can do that, once you have decided to have faith that the real world does indeed exist outside of your own head, and that at least some of your perceptions and sensations reflect that reality.
2) is validated via the scientific method and is certainly NOT a general claim. There are many people whom I do not rust as valid observers. To determine trustability, I use observation and testing.
To perform observation and testing, you are back to #1--having faith in the accuracy of your first-person observations. When the scientific method gets to replication and peer review, then you are at #2--having faith in the testimony of others about their own observations. But for the vast majority of "facts" in most people's lives ("She's getting married in December," "They have three kids," "Your report is due on Friday," etc.), the testimony of trusted others is sufficient to establish fact.
Note that I am not saying this is the best or most conclusive way to establish fact, but merely that many "facts" are indeed based on faith in the second-person testimony of trusted others, just as first-person (personal) experience is based on faith in the real world and our ability to apprehend it.
Faith in the axioms is not required. All that is required to having axioms and rules of deduction. Whether those axioms *apply* to the real world is a matter of observation and testing.
Faith in the axioms IS required if you are to have faith in the theorems as "facts." If I don't have faith in the transitive property, for instance, then I cannot accept that a=c, even knowing that a=b and b=c.
1) All men are mortal.
2) Socrates is a man.
A) Socrates is mortal.
You may accept that 1 and 2 are true, but unless you also accept (let's call it 3) "if 1 and 2 are true, then A must be true," then you are not constrained to recognize the truth of A.
1) All men are mortal.
2) Socrates is a man.
3) If 1 and 2 are true, then A must be true.
A) Socrates is mortal.
But again, you may still accept that 1, 2 and 3 are true, but unless you also accept (let's call it 4) "If 1, 2 and 3 are true, then A must be true," then you are still not constrained to accept that A is true.
1) All men are mortal.
2) Socrates is a man.
3) If 1 and 2 are true, then A must be true.
4) If 1, 2 and 3 are true, then A must be true.
A) Socrates is mortal.
And so on. So yes, you very much have to have faith in the axioms of the system you are using--accept them as being true without proof--before you can do anything useful with the system at all.