For the first you can try something like that (in python) :

users = self.pool.get('res.users').browse(cr, uid, uid)
manager_id = users.default_section_id.user_id.id

For the second, you can take a look on the sequence system already in use in OpenERP (Configuration > Technical > Sequence and Id > Sequences) and add your own.

Both items needs more flushing out to give you a good answer but:

1. You can use the uid passed to a function to get any other information associated with the user that you need.

2. This can be done with serial numbers, you can enable them in settings > User > Access Rights > Manage Serial Numbers and then enable them in the product Sales > Products > click on a product or add a new one > inventory tab > Track manufacturing lots.