In the days of film, that was something to be concerned about. With extremely quick shutter speeds, the film plane just wouldn't be exposed to light for enough time for the film to react. This was also the case with long exposures, making astrophotography very inconvenient as, for example, a 1 minute exposure didn't behave as a 1 minute exposure should behave. There were ways to get around this that required lots of effort, but we don't need to worry about that with digital, that issue doesn't occur anymore.
Regarding long exposure noise, I believe (but not 100% sure) that you'll probably see more noise with a longer exposure, but nothing to worry about, you'll get more noise with a shorter exposure end a higher ISO (for example, you'd get more noise with a 15 second exposure at ISO 800 than a 30 second exposure at ISO 400).
Hope that I helped!
Gear: 7 Nikon Nikkor AI-S and AF-S lenses, SB-700 flash, Nikon D7000, Nikon FM, variety of accessories
"There are no rules for good photographs, there are only good photographs."
- Ansel Adams