[konbini]

You have nothing to worry about and plenty of time to prepare.
It is best to buy small things to give as gifts. Try find something unique to your country. I suggest that it might be cheaper if you withdraw money in Yen using a bank card. Ask your bank about the fees for use in Japan.
I suggest that you should write an itinerary and start looking for places to stay. I hope you first trip is enjoyable. Don't feel you have to see everything because you'll probably want to come back.