Answers (correct nerdy me if I'm wrong)...
1. Sandwich was originally Raimund Marasigan and Diego Castillo on guitars, Myrene Academia on bass, Mike Dizon on drums, Marc Abaya on vox, and Miko Ilas (ako yun) on clappers...
2. Just my opinion here... I guess the name came from th fact that they came from different bands before being Sandwich (Raims obviously an Ehead, Myrene and Diego on The Aga Muhlach Experience, Mike in Teeth. I think they got Marc in an audition.) So different components there making a wonderful combo.
3. Malupet talaga sila. The fact that they have done OSTs for TV shows and commercials without being even a bit commercial is respectable.
4. Yes. He was the vox when their songs were "Two Trick Pony" and "Butterfly Carnaval". Siya rin at yung sa "masilungan", pero iniba yung vox for the vid because ala na si Marc noon.
Thanks for asking Infopop because you need to know... (RIP great late Campus Radio)