Michael:
Your essay here today is right on target, a useful exposition of the present problem's similarities to, and differences from, the Watergate researches and investigations conducted by Bernstein and Woodward and their supporters at the W Post. 
Someone (singular or plural) must similarly set up a chart of the current issues, witnesses and records that need to be developed, fleshed out and probed. Your essay goes a great distance in several directions in this regard, but as the investigation proceeds, those in charge must be ready to adjust the chart.
This so-called presidency is a great scourge being visited upon the USA. Meanwhile, we must realize that the Republican Party ran no one for the presidency in 2016, and the Democrats ran the survivor of the struggle between the ultra-liberal Bernie and the anti-US military Hillary. Getting rid of Trump, et al., with all that goes into such an effort, will not reverse the demise of the Republican Party.  
Vincent in Valley Forge