Equality

The Declaration doesn't say that all men should be treated equally, it says that "all men are created equal".  Then, a little further in, it says "That to secure these rights (life, liberty, and the pursuit of happiness) governments are instituted among men, deriving their just powers from the consent of the governed".  I think that people tend to read too much into this.  The original intent was to refute the old "divine right of kings" theory, which asserted that kings rule "by the grace of God".  The declaration asserts that God did not invent government, God created people and then people invented government, basically to protect them from each other.  Since people invented government, it is their right to "alter or abolish it" when they believe it isn't doing its job correctly.

I think the rationale behind restricting voting rights to property owners was that they were the only ones paying taxes at the time.  It didn't seem to occur to people that much of the revenue the property owners paid in taxes was derived from the rental of their property to tenant farmers.  As other forms of taxation were devised, it became harder and harder to justify the property restrtiction, and it gradually withered away.  I don't think there is anything in the original Constitution about it, determination of voting rights was left to the states.  The 15th Amendment later prohibited the states from denying voting rights because of "race, color, or previous condition of servitude", and the 19th added sex to the list.  The 24th prohibited the poll tax, and the 26th lowered the minimum age to 18.  Prior to these amendments, some states let some of these groups vote and some did not.  The amendments just made it uniform at the national level.