First of all,
is a Tokyo tough guy's colloquial version of
(For those who still believe that 「わ」 is feminine, it is not.)
Next, 「せいせいする」. (「清々する」 using kanji.)
It is a set phrase expressing how one feels refreshed, relieved, etc. after a big problem has disappeared. My own secret translation of the phrase would be:
This 興味深いわね is just "That's interesting" or more specifically, "This '意識思考そのものが自律して...' is an interesting assumption." わね is a feminine sentence-end particle which does not necessarily have to be translated, but it's for seeking agreement; "huh?" or "isn't it?"
興味深い never means someone is interested. For example, 彼は興味深い always means "He is an interesting ...
This is an ending theme from anime 怪傑ゾロリ, and ゾロリ's mama has already been dead for years when the story begins, so...
The の is #❷-1 in デジタル大辞泉:
It's a sentence-ending particle. (With a falling tone) You use it to soften an assertive statement. It's more used by women.
So ゾロリ's late ...
Grammatically, わ always follows the dictionary form of a verb/i-adjective or だ. It never follows the imperative form and ～ください/～ちょうだい. (～ください is etymologically an imperative form.) As a feminine sentence-end particle, わ is used to state a fact or her own feeling with mild emphasis. Unlike わ, よ safely follows an imperative form.
煙草をやめるわ。 I will quit ...