Is it fair to say Okonkwo gets in touch with his feminine side? Does Okonkwo learn anything during his exile or he remains pretty much the same?

I never really saw this. Okonkwo suppresses his feminine side and after he returns from exile is crushed to see what has become of his culture. Okonkwo never admits he is wrong; more than anything he suppresses the feelings of remorse (killing his son) as he sees them as signs of weakness. I think when all is said and done Okonkwo hanging himself is his ultimate form of expression. His steadfast gender identification combined with his sense of masculinity, he sees as compromised upon his return. No, I think Okonkwo is pretty much a static character throughout the book.