Does everything have a beginning and an end to it?

You did not underand what I wrote. Take your time with it. There are very good reason's I sent you to Language and Experience before attempting a resolution of the question.

...just follow the Pantagruel recipe´s lads...the man is a chef !

I think I do understand your circular reasoning.

Do all things have boundaries?
Do boundaries mark the end of a thing?

Now.. How do you propose to prove that all things have boundaries and therefor an end?

Here we go again. When you learned proof in school, did you ever use it to prove a definition? You are headed down the same path of those who tried to prove Euclid's 5th.

So..
The definition of a "thing" is something that has a boundary and an end. Is that correct?

Ask a table. A table is a thing. It is comprised of a material within a form. Synonyms for form are boundary, limit, extremitys, etc.
And since a thing is not different from a thing, you have your answer.
It is not circular. All environmental acquisition systems of a living organism survives by craft. This is true of the human mind. Craft is bringing together form and material difference to create things.
You attempt to reason prior to the study of the principles of predication.

So...
The boundary of a thing is not a thing, nor is it the material difference of a thing.

So.. does this mean the boundary is always between 2 things?

No, a boundary is a divisor of material difference.
one cannot divide the divisor.

There are a great many logical ideas in the works of Plato that no one has got, yet they all follow from the two element metaphysics.

So is "not a table" a thing?

Is a phrase the name of a thing? Does the name of a thing include an assertion or a denial? Don't get me started on the bs in math today. I am actually doing an audio book, and ebook of one of the founding works on this, I will add my critique of course.

The table has a boundary where it (the table) ends and what is not the table exists, is that correct?

The shape of the table is not the table, nor does it exist.
The material of the table is not the table, nor does it exists.
The table is comprised of some material in some form. Just like every thing.

Since material and form are not actually separable, as Aristotle observed, one might come to think of reality as fluid.

So if there is no material in any form then it doesn't exist as well? And it is not a thing?

what is the "it" that you refer to? Can you say "it" at all? The term is used for in situ abstraction by example, of which you just said were not.
I.e. your engaged in a tense error, since you refer to what does not exist at the time of referal.

Is the lack of material or form a thing?

Now you are abusing me badly.

How so? I am simply trying to understand.

No, you are not. You have been given more than enough, but fail to use it.

Perhaps you just aren't explaining well.

A boundary must exist between material and lack of material, must it not?

No.
What you are starting to see, maybe, is a distinction made long ago. Between the perceptible and the intelligble. there is always material on both sides of a boundary.
Long ago, it was understood that both nouns and verbs were names of things. Nouns were names of things perceptible, but verbs the names of things intelligible.
I am trying to write grammar from scratch, but a boudary is always asserted to material.

Grammaticaly, a noun is the name of a thing, but the name targets a material difference and leaves the form undefined. A verb is the name of a thing but leaves the material difference undefined. So that combined, the undefined terms vanish, and you construct a name of a thing with a specific material in a given form. Like blocks that fit together.