[Enigmail] Newbie

[Duke Hound]

Hello,

I am a relative newbie to PKI.  I set up thunderbird/gnupg/enigmail
today and all seemed to work.  Yeah.

1)  With this set up there doesn't seem to be a certificate.  Is there
one in the background? (I suppose not, b/c that would mean I issued my
own certificate...is this why gnupg has the sign a public key?)  When I
sign a key, am i essentially letting everyone on the public key network
know that I trust this public key and in a way being a certificate
authority or is this signature only for me locally?

2) gmail (online client) does not play nicely with GNUPG signatures.
Does gmail (online client) play nicely with verisign Class 1 Digital ID
signatures?

2a) If the answer to 2) is no.  Do any common online email clients
gmail.com, yahoo.com, aol.com, etc play nicely with gnupg or verisign
email signatures?  Is there any progress being made to standardize this
process so that that my choice of signature infrastructure
(thunderbird/gnupg/enigmail) can be made without considering the
technical setup  and understanding of my email recipients?

Thanks,
d