Hi A., HAPPY BIRTHDAY to your litte girl!
I am just waiting for those days when my own daughter starts asking questions about everything under the sun. Kids are curious by nature and are going to ask some doozies, I did. :D
To answer number 1. I would say that kids usually have their balance pretty well intact by the time they are 5 or 6 years old, sometimes younger, sometimes never, lol. Kids will figure it out, even without the training wheels. Believe me, they learn much faster if they get a few scraped up knees than if they have the support of training wheels all the time.
#2 - You have to consider the neighborhood you live in. Your neighbors, their kids, etc. If you live in a nice area, I would say that letting your kid go out in the back yard or enclosed front yard as early as 5 is okay, but even then, you still have to be careful. Backyards, if you have a back door I would let her play outside when its gets nice now. (as long as it is fenced in)
#3 - Now, thats a little tougher. If your daughter is old enough to ask the questions, shes old enough to hear the answers. However, keeping in mind that she is still very young, those answers are best kept to age appropriate language. I have no idea how to explain to an adult about male homosexuality. I wouldn't know where to begin. But you can be sure that if shes asking about death, sex, homosexuality, pregnancy, etc. I don't know what your religious background is, if you are uncomfortable with discussing sex with a four year old or not, but here is what I would do if my daughter asked me these questions.
"Ayla, sex is something that happens between a man and a woman who love one another very much. Usually they are married and want to make a baby." Thats about it A., because even with advanced questions, 4 years old is too young to know the details. Once they find out, they lose some of their innocence and they can never get it back.
When it comes to death, just let her know that everyone dies one day, and it is nothing to be afraid of. If she wants the scientific reason why people die, just let her know that it is physically impossible to live forever and eventually the body wears out, like an old car.
On homosexualism, just explain that everyone perfers something. This is one of those touchy subjects when it comes to kids especially because everything you say can be skewed or misinterpreted. Make sure that your daughter understands that sometimes, men and women like the company of the same sex (age appropriate words) and that gay men are just another aspect of our colorful country.
Yea, that should cover it till she gets older. lol. GOOD LUCK