It is an interesting question. Firstly, because of the science-based tag, it is unlikely that any planetary body could rotate at anywhere near the limiting rotational velocity. Most planetoids in the solar system have a period more than about 2 hours - anything faster is generally very small (sub 1 km) although there are a few exceptions (one object 400 km in diameter with a 30 minute period is listed in a wiki article). It is not obvious how normal planetary creation or even a violent collision could give an earth-like body anywhere near that rotation rate.
But allowing for some wierd natural phenomenon (or artificial means of spinning up), a rapidly spinning body can form into a stable oblate spheroid or a rod-shape or a multi-lobed structure (or even a torus).
Assuming the oblate spheroid option, the maximum stable spin is when the surface gravity at the equator is equal to the centrifugal force on an object at the equator. That means that a body at the equator is (almost) in geo-stationary orbit. Any faster and the planet will fly apart.
I don't have the maths tools here to do a detailed calculation but for the earth, I believe the limiting obaticity is around 3:1 so the earth would have a radius of ~11000 km at the equator but only about 4000 km at the poles. It would be rotating approximately once every four hours.
Effective gravity at the equator (that is the sum of the effects of gravity plus centrifugal acceleration) would be almost zero - i.e you would be nearly weightless. At the poles gravity would be about 2/3 of what it is on earth. Interestingly though, on the oblate spheroidal surface, the local 'down' would still be perpendicular to the surface at every point (assuming the planet was in hydrostatic equilibrium) - although the horizon would appear much closer at the equator and much further away at the poles compared with Earth.
With regard to intense winds etc - the rate of rotation and the oblacity wouldn't in themselves cause excessive winds - but they would likely result from a combination of solar radiance (heating the atmosphere) and the Coreolis effect (which would be much greater than that which we experience on Earth). But whether this would cause mega hurricanes, or rapidly circulating latitudinal air-flows like you see on the gas giants is in the realms of exoplanet meteorology so I cant really comment. In principle there is no reason why the atmosphere might not be relatively stable.
On other effect of this oblacity is that if there was a significant axial tilt like earth's then the seasons would likely be a lot more extreme - as the poles would have a surface far more oblique to the sun and the portion of the planet s surface that could be considered 'polar' would be much larger.
No obvious reason why a hardy intelligent species couldn't evolve in these conditions. And they have the bonus that if they can, their rockets would have a much easier job taking off - so long as they built their space-ports at the equator.