The filter is the same for all 4T65's.. Comp g is no different. Same filter fits all the 4T60's as well.

If you are doing just a pan drop and filter you need at least 7 quarts. GM FSM states 6.5, I've found on tons of them that it's more like 7-7.5. If your trans is in good working order then a flush will not hurt anything. The only difference between a service and flush is you have less clutch material suspended in the fluid when you are done flushing. A flush should never hurt a trans.