Would vessels like battleships or cruisers, equppied with railguns instead of conventional guns, be able to offer fire support for ground troops?
Doing my research, I have been informed that railguns would be unable to fire shells equipped with explosive warheads, or anything other than metal slugs. Is this is true, and either way, what would be the best way for surface warships to engage ground targets with railguns.
Yes.
Hypersonic projectiles - specifically shaped to withstand 2500-3000 m/s (Mach 7 to 9) - which burst/fragment close to the target. That cone of hypersonic fragments are guaranteed to take out light armored defenses - by necessity of being mobile and be repositioned based on the attack specifics, they can't be heavy armored.
Non-fragmenting slugs will take care of anything else.
I doubt you'll use railguns directly against personnel.
Railguns can also deliver area of effect damage by detonating a bursting charge in the projectile which unleashes a swarm of smaller projectiles over a large area.
The above from Wikipedia links to Navy Matters and National Review (both links in Wayback Machine).
Yes.
Just wrap a metal layer around the warhead, and design the shell to be exceptionally durable.
It doesn't matter if only some of the round is capable of being effected by magnets; all that matters is that some of it is.
