Yes. As long, as the compound word makes any sense in the context of the sentence that contains it, everything is allowed.
Many established compound words have specific meanings, that du no longer depend just to the context only. For example:
Gasthaus - Gästehaus
Both words are built fron the same components (guest + house), but have different meanings.
About the Fugenlaut
Someone said in his answer, that the letters, that you use to fill in between the components of a compound word would be unpredictable. This is not true. There are rules, but they are complicated, have lots of exceptions and often vary across different regions:
North of Germany:
Adventskalender, Schweinebraten
Austria:
Adventkalender, Schweinsbraten
Differences
You asked about the difference between *»Autogeschäft«, »Geschäft der Autos« and »Geschäft von Autos«?
The answer is: Only »Autogeschäft« exists, the other two are not used. I explain you why with some different expressions:
- Autogeschäft
This is a shop where you can buy cars.
- Geschäft der Müllers
This is a shop owned by some people who's name is Müller. Mr. and Mrs. Müller are owner of this shop. So, »Geschäft der Autos« would mean, that Mr. and Mrs. Auto own a shop. (And there they sell vegetables, or books, or what ever they have in their shop.)
- Geschäft von Jürgen
Same as before. Jürgen is the owner of the shop.
German native speakers invent new compound words all the time. Do't worry about it.