Cheap accomodation wanted

Hello readers, I have to visit Tokyo for around two months for some official work. I am little bit confused about few things.
1) Do the locals in Tokyo understand English?
2) What the weather is likely to be there around this time of the year?
3) Is it possible to get a service apartment on rent for two months? If yes what could be the rate for that?
4) I have checked few site on Internet like asiarooms (dot) com for information on Tokyo accommodation, can anybody suggest me some more sites on the net.

Do the locals in Tokyo understand English?

Some do, many don't. Writing and reading skills are often better than listening and speaking skills.

What the weather is likely to be there around this time of the year?

What time of the year? You don't indicate when you will be coming! Some basics:
http://www.japan-guide.com/e/e2273.html

3) Is it possible to get a service apartment on rent for two months? If yes what could be the rate for that?

Yes, it is possible. There are dozens of companies for people with low budgets (shared shabby apartments from around 40,000 Yen/month) to luxury apartments (several hundred thousand yen/month). Some companies are listed here:
http://www.japan-guide.com/e/e2200.html