User system database design
Having the users and lost passwords in the same table implies a 1-1 (or 1-0/1) relationship; 1 user has 1 lost password (or none, if the column is nullable).

If that's the cardinality of the relationship, having them on the same table is correct. The school of thought that refuses nulls (which depending on the day, I adhere to), says that if the relationship is 1-0/1, you should:

users
  usersID primary key

lostPasswords
  usersID primary key references users(users_id)
  -- lost password columns here, non-nullable


The relationships look fine, however, I would suggest you use a diagramming tool which shows which are the columns referenced. Surprisingly, I've only found SchemaSpy doing this: http://schemaspy.sourceforge.net/sample/diagrams/summary/relationships.real.compact.png