Sort:  

Cool. On to the examples! These are all from the opening paragraph.

What exciting time

Should be "What an exciting time"

We are rushing towards Smart Media Tokens and the general feeling to be here is getting better by the day.

To start, this sentence badly needs a comma before "and." Also, "the general feeling to be here" is not grammatically correct. Maybe "the general feeling here" or "the general feeling of being here" would work.

The 1UP project will bring a massive benefit to communities and individual Steemians and things come along nicely.

To start, there's another missing comma before "and." Also, things "are coming along nicely," not "come along nicely."

The commas before the and were new to me. We never do that in German before an und. But knowing it now makes it easier. I don't really understand the ohter examples gramatically but I get the feeling of why mine looked bad and your example not. That is good enough for me. ;)

Thanks, I am getting the hang of this. Utopian rocks!

I am not that good at many of the underlying rules either. But I do know what is and isn't grammatical.

Here are the simple rules to using commas before "and": The only time you don't do it is when you're making a list with two items. "My friends are called Joe and Jill." If it splits a sentence into two distinct parts, you always need a comma. If you're making a list with more than two items, that's a point of contention. I support using the Oxford comma, so I say you should.