@Sasaki

The definitions of idealist:

1. One whose conduct is influenced by ideals that often conflict with practical considerations.
2. One who is unrealistic and impractical; a visionary.

I don't think those definitions conflict with mine and I think they describe Jefferson perfectly. Your note of him being overly confidant of his beliefs is a symptom of being an idealist everywhere at any given time past, present and future.

I will agree that sometimes the idealistic view is wrong. History gives plenty of examples.
EDIT: See the fourth quote you posted.

The first quote in my opinion is not an indication of being "stupid" but is just in lacking tact. As my girlfriend likes to say when I start bashing religion in her father's house: "remember your audience". Anyone who has seen, lives and breathes death as much as a general and his soldiers do in the middle of a war begins to tire of the needless death that principles and ideals bring about when pitted against each other in a state of power vaccum that the colonies/early US was in at the time. Even if such principles (liberty, freedom from tyranny, all that good stuff) are of the most noble nature.

The second quote deals with Jefferson acting behind the scenes against the policies of Washington. Jefferson was a cabinet member as Secretary of State and his actions independent of Washington were a failure of Washington to keep his cabinet in line. There have been other presidents where the cabinet was left alone to handle their respective areas and the president bowed to their expertise on the matter and subsequently they became more independent from the president and resistant to any meddling when the president did want to take action. Those presidents are looked upon as weak, and Washington should be viewed a bit more harshly in this regard imo since the backlash against Jefferson in that quote would mostly stem from the fact that he simply was going against Washington which is not inherently bad in itself if Washington and other "Founding Fathers" were not deified. It was no secret that Jefferson had huge support for the French, everyone knew it.

In the third quote, Jefferson is completely right. Washington had and still has a cloak of no wrongdoing and deification going for him. All public officials, no matter how loved or beloved must be subjected to harsh criticisms in order to keep the overall power of the man and position in check.

In the fourth quote, it is just indicative that Jefferson in this matter was wrong. For a man ahead of his time in political thought he was behind in economic thought. Blame it on his upbringing in agrarian Virginia or blame it just on ignorance, he was wrong in the matter of the derivation, creation and holding of wealth for the future of human society.

I hope that last statement made it clear I'm not trying to be a Jefferson apologist here.