Hi.
1) Yes. I can do full side splits with my toes up, but not with feet flat and back upright. I always practiced the toes up way as a kid because that's how I saw dancers do it. To have my feet flat I have to have my body flat on the floor. I think this is called roadkill splits.
2) I did lots of relaxed stretching between set of Squats when I was a kid. I had no goal in mind. Someone told me I should stretch between sets so I did.
3) It took between 3 and 4 years to get side splits, although it was not my goal at the time. Just one of many stretches I did while weight training.
4) As a kid I had many minor injuries while stretching, mostly because I was overtrained or overkeen.
![Smile :)](./images/smilies/icon_smile.gif)
I've injured myself a few times in karate, inevitably because of poor technique as I've got tired towards the end of the class and my concentration has slipped. You've got to keep your mind strong and your technique good, even when your body wants to give up
5) I'm now 37. I did side splits for the first time at about 18, before I started Karate. The flexibility came in pretty handy when I started Karate. It helped me progress very fast.
Cheers
Tim...