Inheritance: Regarding inheritance, I believe that women should at least get half as much as men. The Quran was trying to elevate the position of women in society and for more than 1400 years this was more generous than any other system of inheritance towards women. However, there is no reason why we should not do one better and give women an equal amount of inheritance money. There are some scholars who believe that women should indeed receive equal inheritance money today (Look here and here)

Homosexuality: On homosexuality I feel others have explained it better. No one is saying it is unnatural, only that God has made it a sin. It is somewhat akin to drinking alcohol. Alcohol have been used in some form by pretty much every Human society in the past. God, however, has forbidden it for Muslims.

Shariah Law: I think what you may be referring to is the version of this law practice by Wahabi states and ISIS. I encourage you to read about the Islamic Legal system. Despite what you may think, the point of Islamic Law is Justice and not cutting of limbs (does not need to happen, we have prisons now) or oppressing women (also does not need to happen). All I will say is that there is no "one form" of Shariah law, all Shariah law means is law derived from Islam. Obviously if you have a twisted interpretation of Islam you will end up with a twisted form of Shari'ah law.