When I had kids is when I had all the estate documents done. I also joined a Memorial Society rather than buy a burial plot or planned cremation - what if you move to another City?
A Will is a document that instructs the court (probate) on what you want to have done with your estate when you pass away. Certain assets bypass the probate process. Those assets are ones that have their own instructions (beneficiary designations on insurance products, financial accounts, etc.). I recommend against hand written or videos. Best to have it in writing and, at a minimum, reviewed by an attorney. There are certain requirements that the court has, and miss any one of them, and you open up the will to being challenged (did you date it, did you revoke prior wills, did you initial each page, is it entirely hand written, was it properly signed, was it witnessed, was it witnessed properly, is every word legible, what did you mean by ABC or XYZ, etc.)
A Trust is an entity that is separate from you. Assets owned by the trust are also not subject to probate. A Trust can also be a beneficiary for insurance products, financial accounts, etc. Or, they can be direct owners/joint owners. A Trust also has a trustee, which directs affairs of the trust. You can be the trustee when you are alive, and designate someone else (brother's guardian, or another person independent of the guardian) to be the successor trustee.
By having a 3rd person be the Trustee, it minimizes the problem of the Guardian spending all the trust assets in a way that does not really benefit your brother (I presume you want to leave everything to him). For instance, Sister could be the Guardian of your brother, and Uncle be the Trustee. Uncle can set up a monthly allowance, and Sister could request additional amounts as needed. Thus collusion between Uncle and Sister would be required to waste Trust Assets: Sister deems it is in Brother's best interest to have month long vacations in Hawaii - Uncle tells her to dream on.
There are pros/cons to revocable vs. irrevocable trusts. The main benefit is the avoidance of inheritance taxes with irrevocable trusts. But, there are extra burdens/risks with irrevocable trusts.
In general, the more you can avoid probate, the better. For your real estate, one common method is to make a revocable trust the owner of the real estate, with you as trustee. Then it is almost like you owning it. When you die, the trust becomes irrevocable, and the real estate does not have to go through probate. If you have both an irrevocable and revocable trust, the revocable real estate trust could "pour over" into the irrevocable trust - at the time of your death, the assets are distributed (transferred) to the irrevocable trust. That way, only one trust, the irrevocable one, has to have all the complex provisions. Arizona also has a Beneficiary Deed, which may accomplish the same thing.
Since you are green on the issue, it is best to discuss it with a professional. Maybe get some will/trust planning software to educate yourself and draft the outline of a plan. That will save time ($'s ) with the lawyer.
