Commercial leases are on commerical premises obviously, eg factory units. They have higher rental returns than residential properties (around 10%), but also much lower capital growth and generally the tenant must pay all outgoings eg rates etc. Commercial properties also have higher vacancy rates than other types of properties. Commercial leases are much more rigid than residential leases, as they are much harder to break out of and they are often long term, eg 10 years. Maximum commercial LVRs are around 70%.
A 5x5 lease is a 5 year lease with four additional 5 year lease options, meaning a possible total of 25 years all up. A 5+5 lease is a 5 year lease that has a single additional 5 year option, meaning ten years all up. These type of leases give the tenant more flexibility in their lease, and these types of leases are quite popular for businesses in the establishment phase, should the business fail, they aren't locked into a long term lease.
'Is it possible for someone to own the property for over 20 years paying rent?', i'm assuming you mean a tenant, well such long term leases as 20 years aren't as common with smaller businesses, but some larger businesses often take out longer term leases when they know that they definitely won't be needing other premises. For example, a car dealership business would be more likely to take out a 20 year lease than a takeaway shop owner.
