would running Electrum behind a VPN be sufficient to obscure my IP address?
Yes, but only your IP. The server stills gets a list of your addresses (which could be bad for privacy).
Electrum is a convenience that obviously costs a bit of privacy. If you want full privacy, then running a full node is probably the answer.
how does the Electrum node aggregate your addresses to your particular wallet? is it b/c your specific request for your addy's are bundled or linked to a specific session?