Purging in this case,is total replacement of all transmission oil. I followed the majority method of draining trans pan 3 1/2 quarts and replacing that, then with the send pipe to the trans radiator disconnected and a big clear bottle under it with a 1 quart marker on it, then started motor and when 1 quart of oil had pumped into catch bottle, stopped motor, filled trans with 1 quart of fresh oil and repeated the 1 quart out, 1 quart in process. At 13 quarts, the oil was clear from the send pipe and the job was done. Needed 1 1/2 more quarts to get hot motor running up to hot mark on dip stick. This is a less harmful method of purging unlike the shop method which puts an external pump into the system that uses more pressure than the tranny pump. Many people discourage the shop method as it can dislodge more crud that can just upset the whole apple cart. Purging is such a lovely word, has many uses !!
As for the filter, that's all I know, it's what is on the box.