

It pays off once more than one person is packing, you carry enough SKUs that grabbing the right items matters, and packing happens in one spot rather than wherever you're sitting. That’s roughly a few hundred orders a month and up. Below that, click-to-print on its own will probably do it.
Pick lists and scan-to-print both come with Pro in the Shippo web app. Pro also includes up to 10,000 labels a month at up to 90% off retail across 40+ carriers, and estimated delivery dates next to every rate so you're not paying for speed you don't need. Every account can try Pro free for 30 days. See plans and pricing.
Three things, and none of them take long. Install Shippo Print so Shippo can reach your printer. Then go to Settings → Printing, set your label print initiation to scan-to-print, and turn on order barcodes for your pick lists and packing slips. Last, set up package templates and rate defaults so orders arrive with dimensions, weight, carrier, and rate already applied. That's what lets a scan carry all the way through to a printed label without stopping.
Most scanners on the market are compatible. Any barcode scanner that operates in keyboard emulation (HID) mode and can read Code 128 barcodes will work. Most retail and warehouse scanners support this by default. For printers, thermal label printers and standard desktop inkjet or laser printers both work.
Yes, in two ways. You can connect more than one printer at a single computer through Shippo Print preferences, then set one default for labels and another for documents like pick lists and packing slips. Using the same printer for both works fine, too. And if you have more than one packing station, each one gets its own Shippo Print install with its own printer, and scan-to-print works independently at each.