Hi

For the first question you can set default value for specific field from "Set Default" option in odoo, Activate the developer mode > From the bug mark in the upper right of the screen > select "Set Defaults" this will be shown

you can select any field to be as defaults when creating any record 

For the second question: Create new Stage with the name "Lead Processed" from Sales > Configuration > Stages >  and you can drag it to the beginning of the list from + mark on the left of the record

When you are creating a lead it will be marked as "Lead Processed"