this sentence means your friends can help you a lot if you want to do something.and the more friends you have the easier you success.

It's correct.“在家靠父母，出门靠朋友”"Rely on their parents at home, go out on a friend" is wisdom. If you go out and leave your parents,it's very important to have more friends.because they will help you.

surely “出门靠朋友，朋友越多越好” is correct =) well done. For natives, we usually put “在家靠父母，出门靠朋友" together. The use of this wisdom is similar to "no pain no gain" you just use those two terms together. if you wanna use it in oral, you might go for "一个人在外面，朋友越多越好。在家靠父母，出门靠朋友嘛。“ in this way, you can conclude your idea of "the more friends the better" at the end of your talk with this wisdom.