This is entirely up to you. If you are comfortable, you can create the document on your own with the help of an online tool. Hiring a law firm that does this day in and day out will expedite the process at a cost.
The short answer is yes. The biggest reason is that not all of your assets will be included in the Joint Revocable Living Trust. Also, a will covers other things that a living trust cannot. For example, the will can specify the custody rights of the children and other wishes not concerned with properties and assets.
All revocable living trusts, just like living wills, can be challenged in court. Dissatisfied heirs can choose to stake their claims and enlist a court to rule on them. In contrast, Irrevocable Living Trusts may have better protection against challenges.
Couples often go with the Joint Revocable Living Trust to lower the administrative costs. But in any event, the legal fees can add up and so are the fees of the trustee or trustees.
The purpose of the burial trust is to pay for the expenses of the funeral. People choose to create a burial trust to lessen the burden on family members and perhaps also to ensure that they get a proper burial. The trustee would take care of everything.