What is the optimal anti-platelet/anticoagulant strategy and duration following a left atrial appendage occlusion with a watchmen device and is a CTA good enough to assess if the device is well seated and without any peri device leaks?  

There is no guideline based answer. Based on observation: High bleeding risk patients: half dose apixaban for 45 days, then confirmation of LAA successful closure with TEE/CTA (depending on centers preference), followed by antiplatelet monotherapy (usually ASA or clopidogrel).