Lipofuse is not a product that is properly regulated as a "drug" - consequently there is no data available on potential interactions with prescription medicines.
If you are keen for medication to help with weight loss then far better to use a prescription only product - these are proven to work and their side effect and interaction profiles are well known.
Products such as Lipofuse have not be subject to proper clinical trials to demonstrate that they actually work - I would urge caution in spending your money on these and suggest that you do not rely on anecdotal evidence nor testimonials form "satisfied" customers.
Varies from patient to patient and also with what is available in your country.
Orlistat has been around the longest and has a good safety profile.