Why did she have a desire to rule over her own domain and people?
With all the power and essence she had, why was she not able to detect the enemy scheming?
When she is offered the ring by Frodo, she turns monstrous for a moment and claims if she had the ring, she would be a powerful queen who everyone would love and despair. What does that tell about her core self?
Why does not the ring have that temptation and corrupting effect on Frodo?
I despise the special effects in that video clip, why'd you have to post that garbage?
Some of the questions you ask, I don't think are answered.
She's obviously ambitious, and that drove her more than the feelings of revenge and possessiveness that drove Feanor and his clan to break with the Valar. She also clearly states she desires power, in order to do good, but she is very aware of the corrupting influence on power.
(She very clearly sees her choice as remaining in Middle Earth and claiming power in order to accomplish her goals OR accepting she should not wield such power and returning to the West.)
The hobbits in general care less about power, compared to the other races. They have a simpler day to day existence, are less pretentious, and are more interested in enjoying what life they have on a personal basis. Note that Gollum owns the ring for MANY years, and Bilbo owns it for a few decades, but what do they use it for? Turning invisible to suit their small needs (like hunting for food or disappearing from the view of social pests). They don't really have any ambitions to use it as a means to dominate. Tolkien viewed hobbits as a simpler, less ambitious race.
Frodo is actually portrayed as more pure in general than even your regular hobbit. He seems above any of the common rural pettiness. He's a bit aloof from the other hobbits throughout the story, set apart like his uncle Bilbo (his parents also died when he was young). He has nothing to gain from bearing the ring but feels a responsibility to do so anyway, and he has seen its effect on his Uncle and doesn't want to use it. There's this great image of him as a long-suffering angel near Mount Doom, with a wheel of fire at his breast, pronouncing doom on Gollum if he dares to touch the ring again. After the Ring is destroyed, he suffers and finally leaves because the experience has changed him too much so he can no longer be happy in that environment. We basically have a suffering, sacrificial hero; he bears the cost of the Ring's burden and ultimate destruction, even if he is still mortal and can't quite seal the deal.
no mortal can really resist the ring regardless of purity. Frodo goes through fits of madness the closer they get to the Ring's doom, and at the very threshold of the fires he cannot resist it any longer. But out of anyone in the story, aside from maybe Faramir, he is able to resist the Ring's influence for a long time. (Sam, I think, it tempted more -- at one point I think he has visions of himself as a hero, although he too shrugs them off.) Note that Faramir has nothing to prove either, in the book. He's off doing his own thing despite the wishes of his father and I think has come to terms with that. The movie version of Faramir was very different and there's still drama between book and film fans over that depiction.
Basically, the less that people desire power, the less they care for the ring -- they see it as a shackle, not as a temptation.
Even Gandalf, who is one of the "better" characters, refuses utterly to touch the Ring. He fears he would be tempted to use it "for good" but knows it corrupts.
Then it would not be wrong to say that Saruman and Gandalf (and Radagast) are quite different personalities.
To flesh that out a bit more:
Radagast looks very different from Saruman and Gandalf (so picture him off to one side in his own sphere, so to speak).
Then you have Saruman and Gandalf who look more similar on the surface and move in similar circles... but once you get down into their core motivations and such, they differ much more than anticipated.
Put another way, the word "fire" is both used to represent them at different times -- but Saruman is the fire that consumes and destroys and alters, whereas Gandalf is the fire that inspires and warms and purifies.
