Replying to 7D for first DSLR

Christmas is coming up and I've been really interested in video- and photography for the last couple years so I thought that it would be a good time to invest in a DSLR. I've been filming with just a gopro lately and I've taken a couple photography courses at school so I have a basic knowledge on the functions of a DSLR.

I started browsing some used dslr's and I found a deal on a new Canon EOS 7D with an EF 50mm f/1.8mm lens for just 600€ which seems to be a great deal for a new dslr, even though a 7D might be a bit "too good" for a beginner.

So... I'm wondering about the lens. I know a 50mm is a "must have" lens in your kit but will it be suitable for freeride and mountain photo- and videography? Will I need another lens with an adjustable zoom?
Any lens recommendations in the lower price range?

Should i go for it or look for better options?