Do people sign my subkey? So, I've generated my GPG key pair. Created a subkey for signing and a subkey for encryption. Exported the whole thing, removed my master key pair to a secure place, re-imported only the subkeys. Now, I take my fingerprint and passport to a signing party and folks verify my identity and go pull my key off a keyserver, sign it, and upload it back to the key server. 

After refreshing my keys I now have their signature on my private subkey? 

Does that mean upon receiving a signature from someone else I need to go get my master key pair and sign it with my private subkey or?

If I lose my laptop before transferring signatures to my main keypair they are lost forever?
See this explanation. The 0x10 signature (typically belonging to a different individual) is applied to one's master/primary key, not to 0x18 subkey signature packets used for signing, encrypting, and authenticating.
Remember, CA responsibilities are decentralized with the PGP Web of Trust and the one's master/primary key can be used to sign other people's master/primary keys that also act as a reputation. By signing other people's master key(s), those people can revoke and re-issue subkeys as needed (with their reputation) without the involvement of those that have applied 0x10 signatures.
With more recent gpg code, the signing subkey will have a 0x19 backsignature when created.