Leolaia,
I have to disagree in your assesment of the great crowd. The great crowd at 19:1 is ambiguous, only a voice from heaven. The leap required to use this as proof of the great crowd's location in Rev. 7 is not convincing. The temple is confessed to be in heaven on several occasions as you highlight, yet each provide the specifier "in heaven," lacking in Revelation 7. The temple at Revelation 9:1 also lacks this specifier and contextually I doubt you would dispute the location as upon the earth.
While commented on, you seem to overlook the distinction between the great crowd and the martyrs in Rev. 6. The great crowd has "washed their robes and made them white in the blood of the lamb" (7:14) while to each of the martyrs "was given... a white robe" (6:11). The former would refer to the acceptance of Jesus' sacrifice while still living. Similarly, the martyrs are told to "rest" while the great crowd "serve him day and night" (7:15)
"Before the throne" is an expression generally reserved for heaven, but not excusively (20:12, Targ. Pseudo-Jonathan Ex. 15:17) . They are "before the throne" not because of martyrdom, but because they have made their robes clean with the lamb's blood (7:15).
TS