River Bus?

Is the river bus in London included with your oyster card and is it included in your daily cap? What are the hours of operation for the river bus in July?

All the information you want is here: http://www.thamesclippers.com/

Yes you can pay with an Oyster Card.

Note that they are not the only boats operating on the river. City Cruises, for example: http://www.citycruises.com/ do a more leisurely tour with a commentary.

The word 'included' is the tricky one :)

You can pay and get a discounted fare using credit on a pay-as-you-go Oyster. The fares are not part of the daily cap, and don't take account of hop-on, hop-off use of the Clipper - so if you are considering several journeys on one day you may be better off with one of their River Roamer tickets.

Some more info here too

https://tfl.gov.uk/fares-and-payments/fares/river