Permissibility of donating blood

Assalmualaykum wa Rahmatullhi Wabaraktuh
From Bangladesh
I am a university student. I involve and work for a voluntary blood donors organization. Our aim is to find blood for patient. When someone come to us we search blood in dormitories from resident student. This is totally free, We cant take any charge for this. Mention that, who come to us for blood these people are very needy and come from village.
Now my question,
1. Can I involve (work) such type of organization?
2. Can I donate blood for regular interval?

3. What is the Islamic Shariah about blood donation?