Sorry to say, but all of your conclusions are wrong.
Islam is not just a religion who teaches to love your family only. It teaches you to spread love to other of your kind; Humans, as well as other creatures on earth.
Let me answer to your question in parts; sounds like Integration by Parts hehe..
One only converts to Islam, when Allah blesses him and takes him out of the group of people of ignorance. When a person converts to Islam, he is never the same he used to be. Islam teaches him to spread love and message of Allah till his last breath. Islam teaches its followers to always be humble and polite to others and to help them in any case.
Allah has told humans to marry a man to a woman, for continuity of their race. Not only men but animals do so. The only difference between humans and animal is that humans take an oath to always be faithful to their lady and to be with her in days of thick and thin.
In Islam marriage's main part is Nika'h. In which both; man and woman, take oath to always stay with each other and to be loyal to each other! Man takes oath to give his all attention and time to her.
Marriage at any time has no offense. You can marry at 18 or you can marry at 50, its onto you. There is no other revelation that would stop you from doing so. Its just your own matter.
As far as children are related, no child calls his father as his grandfather! That is a lie. They might call their dad to be overaged father but they won't confuse him with their grandfather. And you know it. So this part has no confusion at all. It is okay to marry at the age of 50-60; if you can!
If one doesn't marry
If one doesn't marry, its their own matter and their own life. We should just try to advise them to marry. But if they don't want to do so, its their own will!
It is also known as Eid of Happiness. You don't need a family to celebrate this. It is an holy event and you need to be and have to be celebrating this with other humans specially Muslims, but you should count others in the happiness and joy of the celebration. Such as, Christians, Hindus, Sikhs etc! You must count them in your event.
They should be their, otherwise it would be just a simple and ordinary event for your own family to cook sweetdishes and serve them to yourself and your child.
You need to spread the word!
Getting married to Religion
Allah only allows us to marry people of our own species. You cannot marry other animals either. You marry a girl; if you're a boy and vice versa. You cannot marry to Religion, because Religion has nothing to do with your life. You need religion, religion doesn't need you!
Some people here in Pakistan marry their daughter with Quran. That is just to prevent that girl from asking for her rights in Wirasat; the wealth left over. That is just bullshit, Islam prevents one to marry himself/herself to any religion; Islam, Hinduism etc.
If you want to keep learning and enjoying religion, you can do so. Holy Prophet (PBUH) did so, yet he was married. He is the Greatest person in the History of Mankind, we should always follow his lifestyle. He was married, to female and not to the religion he was sent for.
All other information is just man-made! They are fake, and will make you falsified.