Employee Ownership Plan

After a recent promotion I'm in the midst of negotiations for ownership. We are privately held. I'm the first employee to negotiate for ownership - meaning I have a blank slate for how I want it to be structured. I'm concerned with a few things. I'm not really interested in having the liability of actually owning a part of the company. Also not interested in paying taxes until I realize some type of gain. Given those two points I'd like something related to phantom stock. I'm also concerned with the liquidity of the shares...when I want to sell how can I guarantee there is a willing buyer? Here's what I have so far:

Ownership form
a) Legally documented
b) Non-liability (Phantom)

Value
a) Determined by agreed upon metrics (multiple of earnings)
b) Earnings defined as: EBITDA less owner draw and benefits

Owner Draw
a) All owner draws must be base-lined at time of ownership grant
b) Any increase in draw by one owner will require disbursement to all owners based on % owned

Stock Rights
a) Buy/sell agreement allowing sale of shares at any time
b) If no owner wishes to purchase, company required to purchase value of shares within 90 days
c) First right of refusal for purchase of any available future shares
d) Rights to annual earnings equal to % of shares in company

Any thoughts on the points I have? Any thoughts on what I might be missing?