How many points are there on the X25519 curves? The order of the base point, $l$, is 2^252 + 27742317777372353535851937790883648493

However, the base point group is nested within other large groups, the largest of which is of size $8l$.

There are also nested small subgroups, the largest of which is a small subgroup of size $8$.

Is it therefore correct to say that the total number of possible points (on either Curve25519 or Ed25519), including the identity point that both the small and large subgroups share, is: $8l + 7$
No the total number of points on the curve is still $8l$. 

The curve order (total number of point on the curve) is simply the subgroup order multiplies the co-factor. This is true for all subgroups. 

For the small subgroup of order $8$, its co-factor is $l$.