The CEO of a LLC early startup plans to assign non-dilutable equity to the founders. Each founder will take a small amount of equity, leaving a pool for future employees and investors.
IMHO, what will happen, actually, is that each founder will be receiving pre-diluted equity.
This seems to raise the risks for the founders and may have other negative effects for the founders and even for the company.
Let's pretend that this was a corporation with, say, 100,000 shares. Your idea is that each of the four founders gets 5,000 shares each, and the other 80,000 shares will be used for investors, to compensate employees and so on. Implied in that is that the founders won't go below 5% each. (Unless the company amends its certificate of incorporation to authorize more shares, which might require the unanimous consent of the four founders.)
There's nothing wrong with that sort of setup. Heck, it's the typical way of doing thing if you ignore the parenthetical.
That's amazingly easy to do in an LLC operating agreement as well: "The company shall not issue additional membership interests if such issuance would result in any Founder's membership interest falling below 5% without the consent of such Founder."
As to your questions:
That's just generalities. You should talk with your own attorney about your specific situation. (And, no, that's not me.)
I don't know the formal terminology behind it, but in our first incarnation we had equity in an LLC by the firm, and we just didn't know how to use it well. Because we were new to starting companies, we had originally created this firm-owned ownership share (meaning, owned by the LLC and not by a particular member), and in our experience it wasn't very useful. Now granted that we were functioning on bare-minimum levels of legal intervention and we were bootstrapping, I don't know if we had the expertise to use it well, in hindsight. We became a corporation, with share issues, and the dilution was much easier to forecast.
I don't think it's a dilution issue in your case because if you have equity that exists already and has been part of a valuation calculation, that's been factored in. It exists, with a value, and the act of allocation doesn't dilute a founder....