A:Answer No to dual-tray; yes to both legal/letter.
Some of Brother's higher-end machines - e.g. MFC-L5900DW or MFC-L5705DW - have a flip-out "multi-purpose tray" that can hold up to 50 sheets of paper; they can also stack on multiple full-sized input trays (but those are an optional purchase).
The flip-out tray on this machine, and on the MFC-2710DW, looks similar but is only rated for one sheet of paper at a time; they call it a "manual feed" tray rather than a "multi-purpose" tray.
The main input tray, and the optional lower trays you can get for the higher-end machines, are adjustable for multiple paper sizes: there are pre-set stops for letter, envelope, legal, A4, A5, and A6 - but you can also set them for multiple sizes in between.
The manual-feed tray on this machine, and the multi-purpose trays on the higher-end machines, have a sliding width adjustment but no adjustment for length - you just push the paper up against the intake gate.
