One question i am still wondering till this day is when Desmond asks Locke
"What did one snowman say to the other snowman?"

Obviously it is a coded message. Does anyone know the true meaning?

It's what Kelvin asked Desmond after he crashed on the island. I've assumed that Kelvin was told by Resinski that when a replacement arrives to ask him that coded question, the correct answer would mean that they were the replacements. Unknown to Kelvin and Des (up till the Losties came along) Dharma had been purged and no replacements would be coming.

Did Kelvin ever say how he got into the button-pushing position?

The correct answer was "do you smell carrots"? This is what Desmond told Locke down in the hatch early in Season 2.

Regarding Kelvin, in or around the same episode he told Des that he had joined the Dharma Initiative and was told that he would be "saving the world" with his work in the Swan.

My understanding was that Kelvin was the replacement, but I think the Purge took place LOONNNG before he arrived, so who did he replace?

__________________
"The Naked Gun!"

Frank Drebin remembers a lost love.

Frank: It's the same old story. Boy finds girl, boy loses girl, girl finds boy, boy forgets girl, boy remembers girl, girls dies in a tragic blimp accident over the Orange Bowl on New Year's Day.

Jane: Goodyear?

Frank: No, the worst.

Oh, right, I forgot about that conversation. Kelvin must have been replacing someone as the system calls for a 2 person team, I never even thought of that. Who was Radzinsky's original partner?

That's right, i completely forgot about the conversation with Kelvin and Desmond. Thanks for the clarification.