Just want to hear what we need to do to set up a simple plan to make sure just in case our kids are taken care of as we would want them to

A few thoughts: Term life insurance is probably best - to make sure they get money to take care of them. A trust will be simpler and faster than a will - you could have trust as a beneficiary of the life insurance. You should find someone you like and trust who would assume custody and take care of your children. We found someone in our community we are friendly with and whose kids were friendly with our kids. We asked them if we could put them in our will and they agreed. We also wrote that if for any reason they were not able to do it, then our rabbi should find another family - preferably one in our city so that our kids wouldn't need to move. Keeping our kids in Chicago was a priority.

You need a halachic will if you want your daughters to inherit. (Or a wife to inherit from her husband more than just basic living expenses +kesuba)

A halachic will also avoid the first born getting double - as compensation for all of the extra mistakes they experienced.

'Avoid' isn't the intent, it's actually a mitzvah according to many. Halachic wills usually set aside some fixed amount of money that satisfy the Halachos of inheritance, and everything else is bequeathed as gifts retroactively