2,500 yen for each time you use transportation in Japan, or 2,500 for the whole trip? Same question for the food.
If counting the money, Tokyo can cost you about 2500 yen for transportation (using non-JR trains), food will take you about 2800 yen
You think it'll be fine to go ahead and try to live/visit such as you are doing without any serious experience with the Japanese language, and do you think it is hard to learn?
Then the language. For all well's sake, study! And start it well beforehand. There's no point in going to Japan without any knowledge of its language. The kanas and about 25 kanjis with a good array of vocabular options give you some chances of speaking with Japanese and even going through the JR train system. Although all Japanese study English on a daily basis, there's no usual level they should be - therefore to know Japanese has more meaning than going there wishing it'll all be OK.