OMG I was a virgin at 21! 18 does not mean anything, it does not change you a tiny bit.
Hold a tip of a condom and just put it on, your foreskin does not have to be retracted.
What it's like to be inside a women? that's from the series of questions "What it's like to sneeze" or "what it's like to cough" or "can you explain how does the orgasm feels". There are no answers to it.