They typically work on a cash basis. Lumpers can be pretty expensive depending on the type of freight you're dealing with. Most companies pay this expense for company drivers - or pay according to how many pieces of freight you have. Some companies will pay a lumper more to unload than they will pay the driver. Some companies allow toll roads, some do not and some will allow only certain ones.
Toll roads can be extremely expensive.
Down time can get expensive. Yet others will advertise home every weekend - there are many, many different ways that companies do this. Typical could be anywhere from 3 to 6 weeks. Some are longer, some shorter and some will base it on how you're doing and the reports they are getting back from your trainer. Most companies have a Probationary Period - even for their experienced drivers.