Does my husband need to create a cover letter stating he will accompany me and he will provide all expenses?
Yes, if those things are true. If there will be sources of funding other than your husband, then the letter should state that. For example, if the hotel is paid by his employer, that should be mentioned in the letter. But in general it is important to have a statement from him concerning the circumstances of the trip.
Also, if someone else is paying your husband's expenses, for example an employer or a client, it might be a good idea to get a statement from that party acknowledging that you will be traveling with him as well. If that would prove too difficult, it might be okay to omit it.
Also, one of the requirements is bank certificate? can I just provide my husband bank certificate? because I am only a housewife and I don't have one. I am just relying on him.
Yes, you should definitely provide your husband's bank statements, since he will be paying for the trip. If the account is in his name only, you should include an explicit statement that you have no bank account in your name.