budget for a backpacker would range from S$75~S$200, unless you take 野宿 as some jap travellers do. Providing you are travelling in early april, it could be cold to stay outside unless you are well prepared.

cash is the king in japan. credit card is only useful in very big merchandise stores.

and btw, I dunno what is there to see in kobe. It is unusual to put kobe in the itinerary.