Capacity is not to hard. Discharge the pack with a Powerlab. Watch the cell voltage during the live discharge. It will steadily decline, then drop off suddenly. As soon as it starts to drop quickly, stop the discharge and check the mah out. that is probably approximately 90%-95% if the pack's originally rated capacity. Don't let it fall below 3.4v per cell during the discharge.
For the C rating, the IR can be a good indicator. Use the IR values with the spreadsheet from this post to get approximate C rating.http://www.rcgroups.com/forums/show...01#post20484169
Max charge rate will be the hardest. In general, any pack 25c and above should be capable of at least 3c charge. For anything higher than that, I'd want really want to know the mfg supports it. 20c, keep it to 2c. Below 20c, its probably not worth keeping the pack.
What's the story behind the question? Have a pack like this, or just curious?