You almost certainly need new pads if fluid contaminated them, and it's probably not a bad idea anyway, since a wobbling wheel bearing can wear the pads on that side prematurely. As for the caliper itself, it may depend on how well you can get the piston back in, and whether you can do this without damage either to the dust seal or the piston seal. If there's brake fluid escaping, you certainly pushed the piston out past the seal, so you will have to push it back. The dust seal is the bellows-like boot that surrounds the visible part of the piston. The piston seal is inside the bore of the caliper. It stands still while the piston moves back and forth, and cannot actually be removed without removing the piston completely.
If I were doing this, I'd try putting the piston back in (just press it in slowly, and as straight as you can. A C-clamp should work well for this, but make sure you don't chip the piston which is made of plastic). Clean it up as thoroughly as possible, so that there is no old fluid showing. If the dust seal is off, leave it off for now. Then, using old pads, reinstall the caliper on the disk and push good and hard on the pedal a few times to operate the brake. If there is no leakage past the piston seal, take the caliper back out and reinstall the dust seal if you took it off, put on the new pads, button the whole thing up, and keep a hard eye on your fluid levels and a nose for fluid leaks for a while until you're sure. If there is even a tiny bit of leakage, get a new or rebuilt caliper. It's probably not a good idea to try to rebuild the caliper yourself.
If you can't trust the piston seal, new or rebuilt calipers shouldn't break the bank, and better safe than sorry.