I have found that this is really a good system. Consuming them orally or through your skin is not good for you, so if you keep food out, people religiously wear gloves, and there is good ventilation, there is not too much to worry about. And yes you can clean this way with linoleum blocks. Hope this helps. You might want to try using simple green to clean off the residue.
Corn oil tends to be a little sticky.
Some colors may have a little lead, I'm not sure. It is a chemical resistant lotion. You can buy it at a place like home base. It's pretty cheap. Roll out brayer or clean other tools by coating them in salad oil.