Update: For the rest, if you're looking for exact counterparts to your list of talking points, I don't have the time to look up references right now.
If you just want a general example of malfeasance, look no further than the systematic way the Democrat-dominated Illinois legislature discriminates against third-party candidates by requiring different numbers of petition signatures for different parties to get on the ballot at all. I have no doubt whatsoever that they'd do this for the Republican party too if there were just slightly fewer Republican voters in the state.
This sort of thing varies by location, of course; my experience in Massachusetts has been that there is a lot less of that sort of thing going on than in Illinois. We do have the election-scheduling thing in Massachusetts, though...
I absolutely agree. It should be anathema; people of all parties should unite to vote out anyone who tries.
However, the article talks about Democrats scheduling local elections (e.g., school board) at times when fewer people vote (e.g., odd years). If true (FiveThirtyEight is credible and the article seems well-reseached), I oppose the practice but I don't think it is at all equivalent to widespread programs intended to actually stop people from registering or voting.
Is there evidence of Democrats doing something more substantial?