It's well known that VPN clients might leak their true IP, due to applications like Skype or WebRTC clients or who knows. Moreover, services like Google keep complaining that I connected from an "unknown device" and they lock even simplest services (e.g., IMAP) until manual confirmation, just because I appear to have switched to an overseas IP.
So, I'm thinking of a different setting: for private/sensitive activities, I'll use a Linux system on top of VirtualBox, which has a VPN client on it. The Linux box will have the bare minimum, won't use my regular accounts, won't use rubbish browsers like Chrome, etc. For all the rest, which is not critical and I don't mind much if they track me and send me ads based on what I browsed on Amazon, I'll keep using the host, without VPN and with more basic protection against spies (e.g., firewall, anti-spyware/malware software, using Linux and not crappy Windows).
Question is: will this setting decrease the security of that VM/VPN client? I mean, compared to a physical machine connecting the wifi or the home router directly? Is there some danger that they track the host, e.g., by inspecting TCP/IP data? Can they do other tricks to associate the VPN connection to the host, or some other device in the same home network (e.g., smartphones/tablets, which of course aren't on the VPN either)?