To face up to something - to choose to deal with something (implies it is difficult or unpleasant)
Don’t take a hasty decision – Don't rush a decision. Take your time before deciding.
In the long run/term – long term / medium term / short term. These are shorter or longer periods of time. It will depend on what it is referring to. e.g. his stock investments fell this week, but in the long term they will recover.
Keep in mind – to continue thinking about something
Work out something – to solve a problem
Be obsessed – to have a great interest doing smth or to be crazy about something. yes, and it also implies that it's in a negative way. e.g. 'he was obsessed with his ex girlfriend and couldn't leave her alone.'
Customers/clients – people who receive or consume a product or service for whatever reason.