When treating someone who has CHF with the drug orencia (abatacept) are any diuretics be given?

Depends. Each patient is an individual...Care has to matched to each case. No generalizations are appropriate without knowing the case.
Depends. Orencia (abatacept) has not been implicated in development of heart failure (hf), but has also not been studied in patients wit hf (<1% of patients in clinical trials had hf). While its use is not contraindicated, it would be prudent to monitor your ejection fraction with echocardiogram every 6 months, perhaps bnp blood test in between and starting a beta blocker such as Carvedilol to protect against hf.