Thanks for the very good questions.
The Church welcomes your family with open arms!
Your husband does not have to join unless he wishes to, though he would have to agree to the children being raised
Catholic, on your part, in order for them to be baptized.
For that matter, any baptism in the Church requires that there is a reasonable hope that the children or recipient of the baptism be raised Catholic. This assumes being well catechized in what and, why the Church believes what she believes.
Since local parish religious instruction can be terrible, like it was for me, we recommend solid, age-appropriate reading matter to learn the faith on your own, done within the family.
The Catechism of the Catholic Church, YouCat, or the Compendium
of the Catechism of the Catholic
Church are good places to start.
YouCat is intended for kids.
If the husband did object to you becoming Catholic, you could probably join through the Pauline Privilege. [another page]
Above what I have said, the best place to start is with the pastor at a local Catholic parish.
Try to find one that is faithful to the Church and has a lot of ministries to choose from.