Clarification on Trademarks and Copy right

Rules State that [...]"The video must not contain more than one instance or mention of a commercial business, industry name, brand name, product placement or other trademark" [...]

Are we allowed to show in our video the mobile phone applications that we use (more than one - one only one time)? Equipment and devices? Would that infringe copyright? Should I write to the owners for permission to use?

If I use two devices from the same manufacturer, does this mean I can only show one of the devices?

Are we allowed to use photos purchased online in our presentation?