  We have synthesized and characterized the four different stable phases of Na
ordered Na$_{x}$CoO$_{2}$, for $0.65<x\lesssim 0.75$. Above 100K they display
similar Curie-Weiss spin susceptibilities as well as ferromagnetic $q=0$ spin
fluctuations in the CoO$_{2}$ planes revealed respectively by $^{23}$Na NMR
shift and spin lattice $T_{1}$ data. The Co disproportionate already above 300K
into Co$^{3+}$ and $\approx $Co$^{3.5+}$ in all phases, which allows us to
understand that magnetism is favoured. Below 100K the paramagnetic properties
become quite distinct, and a 3D magnetic order sets in only for $x=0.75$, so
that charge order has a subtle incidence on the low $T$ energy scales and
transverse magnetic couplings.
