Wedding, then backpacking, please advise

My English husband and I(Danish) are going to Japan for three weeks in 8 days. We're flying into Osaka and then spending 6 nights there, because my husband's brother is marrying a Chinese girl there, then we're going backpacking to Hiroshima (2 nights), Fukuoka (3 nights), Tokyo (4 nights), Mt. Fuji (2 nights) and finally Kyoto (5nights) - what do you think of that itinerary? My husband and I are both in our early 20s, and we enjoy a bit of everything eg. city life, culture, nature and night life.
We will be staying at Hostels throughout (apart from in Osaka when we've rented a flat for the week) Are hostels safe enough to leave overflow cash and traveldocs?

With regards to cash, are ATMs easy to come by? Do they usually accept VISAs, and do they charge a huge exchange-interest-rate?

With regards to the wedding, is there anything that is off the limits in clothing and such like? I've got a fairly short (cute) dress that stops just above my knees, is that acceptable?

Are you expected to give presents when meeting a new addition to one's family? What's curtesy is expected?

Thank you very, very much for all your help and insight - I've read alot of other people's Qs and thoroughly enjoyed your words of wisdom.

Anette

in respect to the ATM, just make sure the ATM is either your bank or an international ATM. There are a lot of ATMs in the cities, but they'll only work for you if they are international or your bank.
other than that, you should have plenty of time to do the things you want to do in Japan.

With regards to cash, are ATMs easy to come by?

Yes, as explained here:
http://www.japan-guide.com/e/e2208.html

Do they usually accept VISAs, and do they charge a huge exchange-interest-rate?

Visa is the most widely accepted credit card in Japan, accepted by a lot of hotels, restaurants and shops. It also accepted by JR railway stations. But there are also some businesses that don't accept credit cards.

The exchange rate depends on your credit card company and not on "them".

It is also very common in Japan to use mostly cash. Many Japanese wallets are rich with cash instead of credit cards. It isn't a surprise to see someone purchase a $1000 item with all bills.

the itinerary looks ok. It looks like you will be away for 12 days starting from the day you leave Osaka for Hiroshima and ending on the day you arrive in Kyoto, or Osaka if you plan to stay there while visiting kyoto. . . Are you planning to buy a JR pass? if you are planning to do 1 day trips away from Tokyo then another one on you first day in Kyoto and use the Loop line a lot in Tokyo it should pay for itself.

wedding dress for the guest is: he: black suit with white shirt and white tie, black leather shoe, she: classical costume, knee length, tights, elegant shoe. ( Or of course kimono ). But it depends what is discussed within the family as dress code. But expect the Chinese family members to �gdress up�h for the occasion. You are expected to give a gift, preferably cash in a specific envelope, available in every stationary shop in Japan, white/yellow rope on envelope, ( not gray/black what is for funeral money ).

When you attend a Wedding party of a Japanese couple, you're expected to bring a money gift. But as neither your brother-in-law or his bride is Japanese, I presume that you don't necessarily follow Japanese custom. How about asking your husband about what his brother wants as a gift?

And I think a short-length dress is fine unless its color is white.

Enjoy your trip!