Migration best practices

[Spillage]

When setting up a forum and migrating the content of an existing version under another software package, what are the best practices as far as the order of migration and setup tasks?

Should I run IMPEX and get the data loaded, then tweak the layout/look, or get the general layout and look before importing the data?

And an important question;
What happens with the 'Admin' username from the source database when you import?... how does this effect the vB 'Admin' username?

[LEIVA]

If im sure when you import all the forum the impex will make you a id for that admin called ( imported_admin ) but double check here maybe im wrong