Smalltalk has to be the best language to learn and understand most Object Oriented concepts, combined with the easiest syntax for any language I have met and the most dynamic and powerful environment, is as you say, a religious experience :laugh:

That can be done without a problem. Remember object-receptor -> message is the basic atomic level of operation in OO, that does not mean two objects could not interact together. You could have a third object representing the context action of both objects communicating together and the third object handling the interaction between both. You could have also two objects working on a same job concurrently. It will depend what you mean with "two objects jointly performing an action"

Interesting question, I have to say that Object Oriented Programming paradigm have influence myself in the way I analyse and understand certain daily life activities. The language in particular is Smalltalk which was the one I used when I learn OOP.