If my memory serves me correctly, we have touch on this idea before, so you may want to run a search for previous threads that had many excellent ideas.
I will however, state a caution that the information sheet not be developed for use on the scene of a trauma or medical emergency to provide information to EMS providers. This forum has a number of EMS providers, so their experiences may differ from mine and their input should also be considered.
By training and protocol (at least in the US), all EMS providers will look for MEDICAL ALERT bracelets/jewelry to learn of medical conditions that may alert us of life-threatening conditions and potentially influence our treatment of the patient. However, (again my experiences) wallets and purses are generally taken by law enforcement agents, they may or may not have the time to let us know of the presence of medical information located within your wallet/purse, before we leave the scene. In a trauma situation, my/our first priorities are always the ABCs, many times I/we do not have time to search through your personal belongings, which can in and of itself bring us legal grief. At the hospital, it is a whole different situation and information cards can provide much needed information for medical treatment and contact next-of-kin.
If you have a medical condition we need to know about, obtain and wear a MEDICAL ALERT device. Pete