You can use browser on the Mac if you want to be able to use the latest and greatest firefox/Chrome but for coding and software nothing beats Linux. All the OS X brew/ports etc are just not good enough compared to apt-get.
You can run the VM using VirtualBox in background mode too and then just ssh to it using the Terminal.app or iTerm.app on OS X.
Copy-paste works really well on iTerm so you can copy-paste links from your OS X browser like Firefox/Chrome to the ssh terminal and use it in case you download software using wget/curl sometimes.
For email, Thunderbird/Mail.app both work really well on OS X and that should be good enough unless you want mutt, which you can then use from your Linux VM.
Most likely your production environment is Linux, esp. if you're in a company that is giving you Macs so most likely web development. Even better if you mimic your production environment in your VM and develop on that instead of developing on a non-standard environment like OS X and then hoping stuff works in production. (Tons of devs do this and it makes no sense.)