defaults for where to merge from

As can be seen from my other messages, I'm experimenting a little with 
git and trying to understand how its workflow compares with arch.  Right 
now, my procedure for branching off a remote archive is:

   git checkout -b branchname remote/upstreambranch
   git config --add branch.branchname.remote remote
   git config --add branch.branchname.merge refs/heads/upstreambranch

Is there a reason why "git branch" and "git checkout -b" should not 
automatically do the two "git-config --add"s when the source branch is 
remote?

In case the source branch is not remote, would "origin" be a good choice 
for the "branch.branchname.remote" variable?

Paolo