I don't think any off ice aid can help develop proper skating form. A slideboard can help develop some muscles used in skating - won't make you faster but should make you more stable. Balance work, hip and ankle mobility, all good things to make you a better skater.
But they won't really address skating form, that's an on-ice activity. If you develop excellent balance and range of motion (hips & ankles primarily), your skating will naturally get better the more you do it.
But sprinting addresses the 2nd half of the question - power. If you want to get faster, sprint. If you want to increase your athleticism overall, sprint. It's the rising tide that floats all boats. Sprinting is the holy grail. Get faster on land and you'll be faster on ice. Sprint training is as much about training your central nervous system as it is about training your muscles - Tony Holler 'Feed the Cats' has done excellent work in this area if you wanted to read more about it.