Divorce and custody of children

I want to start divorce proceedings immediately as i have tried my best to adjust and have reached a stage where i cannot suffer anymore.The mental torture is too much to handle for years as my husband is always doubtful about me(even about fatherhood of my child) and now even asking me to resign my job. After 6 years of marriage now I have finally decided to end this and start a new life as my family is also supporting me after understanding my situation.. I have 2 children of age 4 years and 9 months old respectively.How can I proceed with divorce? I am not sure whether he will agree to file divorce by mutual consent.If not on what ground i can file for divorce?How much time &money it will take?I am very worried about custody of my children,i am financially capable of providing to them as I am well employed.If at all he agrees for mutual consent divorce whether the agreement in court will include all terms of custody of children,visitation rights etc?If I am given the custody of my children ,will he always have visitation rights,as this means i will have to be in constant contact with him even after divorce. And finally at any point of time later in my life if i get remarried will it bring any changes in custody of my children,assuming that i am getting custody at the time of divorce?