Well first thing you need to do is help prevent it the best you can. That means making sure that your diet and supplements are appropriate and in enough quantities for laying hens and pullets, especially the first year.
That means no less than 90% of their diet (I prefer 95%) should be a good quality fresh smelling laying pellet. The other 10% can be treats, supplemental grains, etc.
They should have both granite or pigeon grit as well as oyster shell available free choice in a separate container from their food. Oyster shell dissolves and so isn't appropriate as a grit alone, granite and other grits don't provide calcium.
Additionally, it's not only calcium that makes calcium absorb; it also depends on there being enough phosphorus and vitamin D3. Phosphorus in a complete food (laying pellets) is sufficient for calcium absorbtion. Adding much grain to the diet causes there to be more phosphorus, which causes problems for calcium intake. So don't add a lot of grains. D is available in their food as well but since it's an oil vitamin it tends to degrade.
For heavy laying flocks, I like to use a weekly treat of yogurt as it contains both calcium and vitamin D fortification. You can alternately use a weekly supplement of wheat germ oil spritzed on their food for vitamin D (as well as A and E). Don't use much. Spritzing the food with it helps to prevent using excessive amounts. The yogurt will not only provide calcium/D but also beneficial bacteria to boost the living bacteria that are vital to birds, particularly during the stress of laying.
As for the "what if they're stuck", there are some great posts on here about how to remove the egg if you see it partially out. I think experience is a great teacher and so learning through others' posts will servve you very well and help your flock. I don't have egg laying problems now that I supplement, so I can't be of much help there.
Good luck! And please feel free to email me if you have any questions.
