Please help: muslim personal law vs special marriage act

Some Links on Special Marriage Act, 1954 :

1.  https://blog.ipleaders.in/10-things-every-indian-should-know-about-the-special-marriage-act1954/

2. https://mymarriagewebsite.com/indian-marriage-law/special-marriage-act-1954/​

3. https://www.youtube.com/watch?v=wG5tQBJPBNM​

I am not a lawyer but still I will try to clarify your doubts. Please cross check with any advocate, as I may be wrong on some points.

Answer to your Questions is in Serial Wise order :

1. YES. A Muslim Couple can get their marriage registered under Special Marriage Act, 1954.
    In fact any couple can register their marriage under Special Marriage Act, 1954 irrespective of 
    the fact that couple may be of same faith or different faiths. There is no bar for couple of any religion, caste     or nationality to register their marriage under Special Marriage Act, 1954.

2. Since your marriage is already registered under Muslim Shariat Law. I am not sure whether you can register your marriage again under Special Marriage Act, 1954. Kindly check with a Advocate/Lawyer whether first registration of your marriage as per Shairat needs stay in together with new registration under Special Marriage Act, 1954.

3. Answer to this question depends on the clarification by an advocate/legal expert on Query no.2

4. Once a marriage is registered under Special Marriage Act, 1954 your husband cannot marry with any other woman by applying Shariat. As per Section 44 of Special Marriage Act, 1954 Bigamy (marriage to 2 women) is a punishable offence.
If any man/husband whose marriage is as per Special Marriage Act, 1954 if he commits bigamy he can also be punished Section 494 & Section 495 of the Indian Penal Code, 1860, for the offence of marrying again during the lifetime of a Wife.
If a Marriage between a couple is registered under Special Marriage Act, 1954 the inheritance of assets will be as per Indian Succession Act, 1925.

SUMMARY :  However, you can re-marry your husband without any requirement of ceremony (i.e.) Court-Marriage & then register your Second Marriage under Special Marriage Act, 1954. Your registration of 2nd Marriage under Special Marriage Act, 1954 shall govern all issues within your marriage.