In the three panels on the right, those are amounts of yen that the characters are donating/offering to the shrine. Search online for a money converter to get an idea of how much they're donating. Or just divide the values by 100 or 120, which are the typical values of yen to dollars. ATM, though, the exchange rate is 93 yen to the dollar, so the donated values are about $21.51, $53.76, and $107.53, respectively.
Panel 2: "So you can use it."
Panel 4: "Happineeess!!!"
Panel 6: "Pa!... papipupepo!!! Papipupepo!!!"
In the Japanese syllabary , pa pi pu pe po is the order that the p- syllables are said in. I'm guessing the yukkuri Reimu is so surprised her language processes shut down. I don't know any other meaning for it.