Dear Querist
my opinion on your queries are as under:
1.Do I have the right to remarry?
Opinion: yes you have right to remarry.
2. I am not willing to take new husband’s surname as all my official documents and investments are in my old husband’s surname..Can I remain with my old husband’s surname even after remarriage? Will there be any legal complications?
Opinion:- you can use the surname of your previous husband if new husband has no objections. But your marriage with new husband should be registered for future safety.