[antimagic]

Not so, only one of the two solutions is unstable: https://en.wikipedia.org/wiki/Schwarzschild_geodesics#Circul...

Also, this applies only to circular orbits, and does not indicate that a powered ship could not maintain orbit.

[repsilat]

Those orbits are all outside the event horizon. Inside it, all you can hope to do is fall inward as slowly as possible.

[dvdkhlng]

BTW most of what I know about black hole physics is from Greg Egan's novel "Incandescence". Which covers quite a lot of science for a work of fiction (and overall extremely inspiring).

http://gregegan.customer.netspace.net.au/INCANDESCENCE/Incan...