Eight gluons, what are the properties of two of them?

All eight color states for gluons are equivalent in the sense they they are linearly-independent non-singlet color-anticolor states. You can pick any basis you want in this 8-dimensional color-anticolor space, and how you do it makes no physical difference.

(Why eight? Because three color states times three anticolor states minus one colorless singlet state leaves eight colorful color-anticolor states.)

So there are no “other” gluons. None of them are special in any way, just like neither the $xy$ nor $xz$ nor $yz$ plane in Euclidean space is special.

All gluons have color, so none exist in isolation. All have spin $1$, and in the conventional basis all are their own antiparticle.

An analogy: you can view the $W^3$ of $SU(2)$ as the counterpart of the "2 other gluons" of $SU(3)$.

The weak $SU(2)$ has 3 "gluons": $$ W^1, W^2, W^3. $$ As @G. Smith pointed out in the other answer, they are "equivalent" in the sense of Lie algebra.

However, when you pick out a specific direction (representation) to define the iso-spin up and down states $|pm>$, say $$ W^3 |pm> = pm |pm>, $$ then there is a diffidence between the 3 gluons: $W^1$ and $W^2$ (or their combinations $W^+$ and $W^-$) can flip the "color" (iso-spin), while $W^3$ will not change the "color" (iso-spin). Therefore, you can make an analogy between the $W^3$ of $SU(2)$ and the "2 other gluons" of $SU(3)$.

For the case of weak $SU(2)$, Mother nature took a liking to a specific iso-spin direction via the Higgs mechanism and we can tell apart an electron and a neutrino. When it comes to strong $SU(3)$, she is impartial (color blind). Any specific color assignment scheme is just a human construct.