Yes, not sure on any discount considering the lumber shortage we are experiencing. Home Depot will fork it on your trailer for free or deliver it for a fee.
Yes, wait for confirmation it has been pulled though
Since you did not say if this is a four wall or three wall construction; give these number a look. Each 9 foot wall will require 7 studs add 2 additonal for each corner and 2 for the top plate and 1 for the bottom plate. A total of 12 boards 10 feet long. You will have three 1 foot pieces left over if you build a 10 foot high wall. Each 15 foot wall will require 11 studs add 2 addiion for each corner and three for the top plate and two for the bottom plate. A total of 18 boards for each 15 foot wall. You will have one 5 foot piece left over. Most builers will add in an additon 10 percent to avoid an addition trip to the store. You said nothing about doors or windows; understand that each opening will require additional framing pieces. Good luck with your project. you may want to pick up a framing book at your local Home Depot and don't forget to check to see if you need a building permit in your area.
Between 3 and four dollars each, the price fluctuates a bit.
To the best of my knowledge; I have never seen any 2 IN. X 4 IN. X 10 FT. STANDARD AND BETTER KILN-DRIED HEAT TREATED SPRUCE-PINE-FIR LUMBER in my local store marked with the FSC or FSI stamps. To be sure; you can visit your local Home Depot and examine the wood to see for yourself. You also contact the United States FSC Organiztion or complete the following form to seach for local suppies in your area. Enjoy your wood working project and thanks for your concern about our World. https://us.fsc.org/en-us/market/find-products/product-inquiry-form