Quietly credible, on paper.

Yes, when the stock and layout meet the standards banks rely on. Check 21, at 12 USC 5003, makes a substitute check the legal equivalent of the original only when it accurately represents all the information on the front and back of the original as of truncation and carries the required legend. In practice that means the MICR line, the contrast and the security features all have to survive imaging. Order Check 21 compliant stock with the template that matches your accounting software, and run a single test check through your own deposit before printing a payroll.

It depends on who prints the letter. Standard white is designed to run through laser and inkjet printers, which is what happens to letterhead in most firms, where blank sheets are stocked and the letter is added in house. The premium cotton and linen stocks do not run through those printers. If you want that texture, put it on the business card, which is printed complete, and keep the letterhead on stock your own equipment can handle.

Through the secure intake step of the order and nowhere else. Routing and account numbers placed in a design file, a proof comment or an email thread get copied every time that file is forwarded or stored, and you cannot retrieve those copies later. Review the proof for position, typography and the template layout, and supply the sensitive fields through the channel built for them. Any process that asks for bank numbers inside artwork should be questioned rather than followed.

It is worth it whenever a proposal is handed to someone who will pass it on. A folder with a business card slot keeps your contact details attached to the document through the internal circulation that happens after the meeting, which is where loose pages get separated. Double pockets let you split the proposal from the terms so a client can set one aside. If your work is delivered entirely by email, spend the budget on the card and the letterhead instead.