1) No, the delivery address cannot be a station yet must be a private address in Switzerland or in one of the neighbouring countries.
2) The temporary GA travel Card is valid for 2 months; with it, you must always carry a passport or ID card.
3) No, the GA Travel Card is valid to inhabited places such as Grindelwald, but not above. Holding the GA Travell Card you benefit from discounts, see the validity map here: https://www.sbb.ch/content/dam/internet/sbb/en/abos-billette/abonnemente/Geltungsbereichskarte.pdf.sbbdownload.pdf.. The area of validity is commonly known as GA-Geltungsbereich.