Are DSA2 signing keys backwards compatible?

[Kevin Hilton]

>No.  Preferences, including the digest preferences, are not relevant
>here at all.  This is a signature *you* are making.  The digest
>preferences are consulted when someone *else* is making a signature,
>and wants to know if you can handle it.  It has nothing to do with
>what your key needs because your key is not involved.

Sorry I was writing my last reply when I received yours.  Thank your
for clarification. I understand the difference.  However given the
fact that I could produce for example SHA256 hashes, wouldn't I prefer
the same hash length in return for security reasons?

Meaning woundn't it be preferable for the showpref statement to read
SHA256, SHA1, RIPEMD160

rather than
SHA1, SHA256, RIPEMD160

Again, Im aware of the default-preference-list within the gpg.conf
file,  This controls the preference order of the hashes, ciphers with
key creation within my own set of keys.  Other than consulting this in
the gpg.conf file, there is no other place this default list could be
consulted?  Meaning this is no command I could type that would give me
the Hash Algorithm I would be using before signing the document --
once the document is signed its easy to see the hash that was used.

I suppose the same discussion type could be stated with cipher type.
Other than consulting the default preference list within the gpg.conf
file (is there is one), is there any way to predict or show a
preference list in relation to my own keys?

Again if the showpref statement is meant for the other party, is there
an equivalent statement or command for myself?