Must use md for printing, they have special codes for the paperwork you have to do showing you're getting your background done for weapons. And of the dozen times I tried to make an appointment closer to home I never got through to a real person, so I went to Baltimore for the walk-in
I actually took my own photos in front of a white wall with my cellphone, and didn't compress it. You can crop and adjust on the md online application, which is nice because it saves some money from getting it elsewhere. That also means you don't have to take a photo and scan it to upload it onto their site. Make sure you have good lighting, just Google passport photos and you'll see what it's supposed to look like
I can't answer for training because I was exempt, but I believe everyone is backed up at this point so you might be a few months out
3 references are anyone that's not your family that cann vouch for you and have known you for I think at least 3 years. I chose coworkers
Really everything you need is on their website. Just Google md concealed carry and you'll get to where you need to go