Re: Differences between female & male practitioners
I treat male and female the same. Standards for grading are the same for male and female in all dojo to my knowledge. I am sure there is a minimum standard held by the sensei so there will always be discrepencies from shodan to shodan etc, whether you compare male vs. male or male vs. female.
As for the safety issue mentioned. You should never practice beyond the ability of your uke. That being said; most students of kyu grade lack the skillset necessary to make that judgement. For the safety of everyone involved I believe you should begin practice with someone slowly and develop a feeling for the individual.
I do not believe it is about strength. I have practiced with a lot of folks, most if not all are much smaller and weaker than I but when the technique is done properly it is easy to overcome my size and strength.
Ultimately you really need to defer to your sensei for guidance with these matters. After all it is his/her responsibility to keep everyone safe.