Well i hope i am not too late in replying :P'anyways
The character of Kunti is very interesting and cant be put in a single go..
Each of Panchakanyas are unique in their own ways.. Panchakanyas represent five elements and are an ansh of Uma-Parvati; kunti among them represents ether/space
'Kanya' is one who is wished for as per adi parva mbh (kunti- suryaconversation) it doesn't have to do with any physical description or condition, its got to do with mind.
Kunti's life is full of struggles and how she shone and rose above the situations makes her a great woman inspite of the criticism she got wrt karna's abandonment and Draupadi's polyandry but one special point to note is , she isn't a typical mil , not the one who we hold a popular perception about; kunti never interfered with and dominated the household after pandavas got married , she happily gave the reins of her household to Draupadi and after the war took retirement at right time by going to woods .
For relationship with Pandu, her father and manys other things, i suggest you read paper by Dr. Pradip Bhattacharya , its available online . There are many articles on boloji.com under subtitle hinduism ..
Hope this helps, good luck