Yes it is. Have you ever tried Mupen64 on linux? every N64 rom I have ever tried works like a charm. Everything from Mario64, RR64, Duke 3D, Hexen and so on. So it's very possible.
Yes, I have. And no, it doesn't. And it's actually mupen64Plus. mupen64 has been dead for 5 years. And no emulators besides the one in pre-alpha in the MESS project and perhaps the latest project64 beta support any form of LLE, which is a requirement for ALL ROMS. If you read my post, you would have noticed I said that the emulator playing all roms isn't plausible.
Because it isn't. Games like Star Wars Naboo Starfighter aren't playable because they use a different microcode than most all games, and that microcode isn't HLE'd. LLE would be necessary for it to be playable. And LLE emulators are still in their infancy.