Are you saying that the seed coat won't pop off the cotyledons (seed leaves)? If that's so then spraying the seed coat with water might help soften it or you can try splitting it using a couple pins. I usually have better luck direct sowing datura seeds. I rarely use the baggie method for seed germination but as long as you get them transfered to soil very soon after the root emerges there shouldn't be any issues with the transition. If the root is stuck to the paper I just cut around it and plant it along with the seed. It eventually breaks down. To prevent damping off make sure the soil isn't too moist. I've heard of spraying the soil surface with tea or diluted hydrogen peroxide but have never tried it. By the time I see it, it's usually too late. There's also a product called "Damp Off" but I've never used that either. Good luck.