All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger. {C}{C}
First of all, we say that it is acceptable for the spouses to have a dialogue on Islamic matters if this is based on a sound scientific basis, and in the framework of mutual respect between them.
If the wife chooses a particular opinion on an issue of over which scholars have differed in opinion, because she follows a scholar whom she trusts, or that she adopts a particular view (if she is a student of knowledge), then her husband has no right to oblige her to follow a view that contradicts the view she follows, or to harm her with words or action just because she follows a view different than the view he follows.
The jurists differed in opinion about both issues that are mentioned in the question, namely the issue of women covering their faces, and the issue of women visiting the graves.
The jurists differed in opinion concerning women visiting the graves, and whether or not it is included in the permissibility after it had been prohibited. Ibn Taymiyyah said: “The disputed issue, about visiting the graves which is permissible, does it include the permission for women and that the prohibition (stated in another prophetic text) is abrogated, or that there is no permission for them, and that they are prohibited from visiting graves? Also, does the prohibition mean it is a dislikeable act or unlawful act (i.e., a sin)? The scholars have three well-known opinions about this. [..] Some scholars believe that women are permitted to visit graves just like men are permitted to do so; they are of the view that the saying of the Prophet : “Visit the graves, for they will remind you of the Hereafter”, is general and that it addresses both men and women. However, the correct opinion is that women are not included in the permissibility of visiting the graves for many reasons……..” [End of quote]
In any case, the issue of visiting graves is an issue of Ijtihaad and your husband has no right to oblige you to abide by the view that he follows as we have already mentioned. This is with regards to your opinion and his on the ruling of visiting the graves. However, it is not permissible for a woman to leave her home without her husband's permission, whether it is to visit the graves or for any other reason, even if it is permissible.
Allah knows best.