"It's a magically hidden street in London. You would need someone who can use a wand to get you in. And it would be best to avoid attention; some wizards won't react well to unfamiliar 'magical creatures'."

"I can hide the wings and tail."

"That will go a long way. You should also hide the computer; even if it looks like something muggles would have, wizards mostly don't use them."

"It doesn't look like something muggles would have until its invention many decades from this calendar year, no."

"Definitely best to be discreet, then. As for how to get you there, I expect Lupin will be called to testify at the trials; he can apparate you to London and bring you Diagon Alley before or after."

"I would appreciate that."

"I'll let him know. Now, the DMLE will be here soon and I'd rather not explain you; do you have any other questions you need answered in the next hour or two?"

"Probably not."

"In that case I'll see you later; I have classes most of the rest of today, but I've informed the other staff members of your existence and they should be able to help if anything else comes up. Though I would suggest not talking to Professor Snape if you have any other options; he's somewhat short-tempered."

"Noted. Please don't misplace Mr. Pettigrew, I can attempt prison reform but cannot resurrect the dead." He departs.

Despite what Cam's experiences may have led him to believe, most people at Hogwarts are in mortal danger only a very small fraction of the time! 

Oh good! He wanders around attempting to learn his way through the castle.

The castle moves around some--especially the staircases that keep changing their minds about which pairs of floors they want to connect and swinging around like crane arms--but most bits stay connected to the same other bits persistently even if "relative location" isn't always the best way to model it. 

A translucent colorless floating man in extremely old-fashioned clothing floats up and says "Good day to you."

"...gosh. Hello. What're you?"

"Sir Nicholas de Mimsy-Porpington, Gryffindor ghost, at your service. And yourself?"

"I'm Cam, a demon. Demons can make arbitrary material objects! What are ghosts like?"

"A demon? Demons would never have been allowed at Hogwarts in my day. Of course, in my day, they didn't exist. Ghosts are, well, as you see me. Incorporeal, for one thing." He sticks his hand into the wall by way of demonstration.

"That sounds inconvenient! I notice you don't seem to have an assistant with you to accommodate that."

Blink. "What would I need assistance with?"

"Manipulating objects? Taking notes, arranging your decor, I guess this could be a part time thing as you presumably don't need to eat and can get around fine."

"Mostly I just drift around and make conversation."

"Whatever floats your boat, I guess. Are there a lot of ghosts?"

"More here than in other places. Hogwarts is the second most haunted building in Britain, and we have six ghosts and a poltergeist."

"Why are you, specifically, a ghost when it's so uncommon?"

"Well, nobody knows, but there's plenty of speculation. I was incompetently decapitated; Professor Binns died in his sleep and didn't notice; Myrtle was in perfect health until she turned up dead one morning."