I am not licensed in New Jersey so you need to speak with a New Jersey probate attorney if the estate is pending there. However, most states do not allow a representative to keep an estate open indefinitely. Why would this even need done? Once the claims aree paid, then distribution is made as per the will or the state intestacy law. Either the beneficiaries consent to the distrbution or they don't. If they don't, then the matter goes to the court and the court makes the final distribution. While I don't know the exact process in New Jersey, most of the northern states have a procedure where a final accounting is filed with the court and the beneficiaries have a chance to object if they have grounds.
Regarding land, the land is generally vested in the beneficiaries. However, New Jersey law might provide for the personal representative to hold title until final distribution. If that is the case, the land cannot be mortgaged or sold unless either an early distribution is made or the personal representative consents to the sale.
I don't know what you mean by the "will" has to be signed by all parties. It doesn't. The will is signed by the person who died. If some kind of caveat (will challenge) is brought, sometimes the personal representative and the heirs can enter into some kind of family settlement agreement rather than litigate. In such case, nothing can be done until the parties sign and the agreement is presented to the court.
An executor cannot take his fee until distribution is made and the accounting is submitted to the court. The court may have a schedule for reasonableness of fees. While there is generally a percentage recognized by the statutes or caselaw (it could be 5% of the probate assets) it ultimately depends on the size and complexity of the state and any final confirmation has to be made by the court.
Again, I am not licensed to practice in New Jersey and I am not familiar with the precise mechanisms there so it may be a little different than the procedcure in PA. You should therefore seek out your own New Jersey probate attorney for confirmation.
An executor must act with reasonable speed and they must follow the terms of the Will. If there is a specific bequest, it must be delivered unless the debts of the estate exceed the remaining assets. A loan can be taken only if necessary to pay estate expenses during the term of administration. After one year, an executor, upon request, must provide a full account of activities. Under no circumstance is the estate to be held open indefinitely.
This response does not constitute the establishment of an attorney-client relationship. It is also not to be taken as firm legal advice as such would be contingent on a full inquiry by the attorney into the complete background of the facts and circumstances surrounding this matter. The response is meant to be a helpful guide to a question in a manner which reflects the limited information provided by the inquirer.