Can HPV itself cause cancer in penis and oropharynx or do the other risk factors need to be met. Like collection of smegma, smoking chewing tobacco etc?

Synergy. Having more than one risk factor usually raises cancer risk a lot more than just adding up the odds. For penis cancer, HPV plus lack of circumcision is the usual combination of risk factors. For oropharyngeal, the risk is more additive, according to this: http://www.ncbi.nlm.nih.gov/pubmed/27197530.