No need to re-stamp a valid visa. Just carry your old passport with you when you travel. An expired passport doesn't automatically make the visas in it invalid

No appointment... I did mine recently.. handed in both passports for 'verification', waited about an hour, done, no charge😁

I did mine there. The hardest part was parking out front.

No appointment needed, and turnaround is about an hour - Bring 2x2 photos, photocopies of your passport pages, the aircraft manifest, your itinerary or boarding passes, Ask your local BI office for the list of what you need

No, just walk in. But it might not be same-day — mine took three weeks!