As far as the seed goes, this will report the seed:
DBCC CHECKIDENT ("FESD.dbo. Usernames ", NORESEED);
And this will set the seed to 1:
DBCC CHECKIDENT ("FESD.dbo. Usernames ", RESEED, 1);
However, this will cause errors on later inserts if values greater than 1 exist in the identity and the column is unique in any way.
Not sure about how to do the increment step. You may have to re-create the column or table to change that.