Call MPD to make a noise complaint; you can do so anonymously. If you believe the dog is in danger or being neglected call DC Animal Control.

You can't force people to get mental health treatment or addiction treatment. There absolutely are services available, and people choose not to use them . Also, plenty of people go into drug addition treatment and then fall right back in their own ways so it's really not this end all be all you try to make it out to be. There is also housing available, but that often comes with strict hours and rules that drug and alcohol addicts simply do not want to adhere to because they'd rather get high or drink on their own terms. I go by there daily, and I see city, non-profit, or other services there pretty much daily. I also see constant drug dealing and drug use there. You try to paint a picture that these are innocent homeless people there by no choice with no help, and that is absolutely not the case.

Ask customer service or someone stocking next time you go.

Amtrak or fly. Amtrak is cheap if you book far enough in advance.