as you say different for each operation but
In general be prepared to do everything by yourself, i.e. have the contacts set up, the back ground knowledge of passengers likes and hates.
The fuel suppliers have CC that you should have, or a contract supplier. Depends on various factors, mostly related to cost.
Catering is normally the responsibility of the CC, but you should be able to advise her as to what might be the best supplier, cost v quality.
Load sheets, I have heard of them,,,, and sometimes completed. It is your responsibility.
Ground handling, again passenger or company preference, but you need to know who is in the market place.
Number of hours, again wildly variable, it might be 10 hours in month 1, and 100 in month 2...but expect an annual total of perhaps 500.
Hotels, again if lucky your choice.
Perhaps use your own credit card, but usually after a few months you should get a company credit card. There will never be enough credit remaining, so know the accountants home phone number.
Pay might be on time, but until you know the company, be prepared to expect up to 1 moths delay.
Hope you enjoy this mad world of corporate aviation....Glf