1) Where is Hill Valley, California supposed to be?
We all know this hometown of the Browns, McFlys, and Tannens is fictional. But where is it supposed to be, really? In the November 1993/Issue #8 of the Hill Valley Telegraph [HVT], Bob Boyce published an article "A Brief History of Hill Valley: 1850 -1993" with all sorts of interesting gems in it. The most important was the precise geographic location of Hill Valley, California. The city is located "12 miles directly east [of Grass Valley]" and 70 miles from Sacramento. One can reach it via the State Highway 20 or by Interstate 80.
This conclusion was reached from, I've heard, studying some of the street sights in downtown Hill Valley and the map that is at the train station in Back to the Future Part III. Grass Valley can be found on most any maps and atlases (really!), and one can even check the weather forecast out. Yes, folks, it does snow in this place because "both [Hill Valley and Grass Valley] are located at the foot of the Sierra Nevada mountains in Nevada county."
2) How did Marty McFly and Doc Brown meet and become friends?
The only "official" (i.e. from the pen of the creators, Bob Gale and Bob Zemeckis) explanation I've ever read regarding this came in the fourth draft of the Back to the Future screenplay. The details were vauge, at best, and it amounted to only a line Marty uttered to his girlfriend: "A couple of years ago, [Doc] showed up at my house and hired me to sweep out this garage of his. He pays me 50 bucks a week, gives me free beer...and gives me total access to his record collection--he's got this great old record collection."
Strangely enough, though, most fan fic I've read has put Marty and Doc's first meeting to when Marty was a kid. That was also the rumor circulating a few years ago when, supposidly, a BTTF prequel was in the works called "Back to the Beginning." I never really thought about Marty and Doc's first meeting prior to reading this line, so I don't know and cannot tell if the friendship is implied to have begun earlier than Marty being about 14 or 15. Certainly Doc and Marty are good friends, but as we cannot "hang out" with them prior to Doc's DeLorean time machine creation, one wonders if the time machine events helped deepen that friendship even more.
3) What were Doc and Marty's address and phone numbers?
As I'm sure almost all of you know, Doc Brown lived in his garage in 1985, the only remainder of his mansion that burned down on August 2, 1962, according to an HVT clipping in Universal Studios Florida. According to another article in the HVT, specifically in the May 1994/Issue #11, Doc Brown's garage/house address was: 1646 Riverside Drive, Hill Valley, California 95420. His phone number was (916) 555-4385.
Marty's address is more of an enigma. His house number was 9303, and this can be seen in the exterior shots of the McFly residence in the BTTF films. The actual street could be many things. Perhaps it corresponds with the name of his neighborhood (i.e. Lyon Estates Road, Lyon Estates Drive) but not necessarily. I've many friends who live in named neighborhoods, but the actual names of the streets are completely different.
While visiting Universal Studios Hollwood in September 1997, I located Marty's work phone number in one of the rooms they put you prior to boarding the DeLorean. There is lots of stuff decorating the walls (like that old HVT clipping about Doc's mansion burned down) and one of the things I saw, scrawled at the bottom of a note pad in a locked case, was labeled as Marty's work phone number. I snapped a picture of it, and it turned out, the writing quite ledgible in the snapshot. That phone number would be (916) 842-3138.