how to tell what size trampoline mat I need?

Well it's too late but in future you can get any high quality best trampoline parts like mat, pad, spring etc from Fun Spot Trampolines .

I don't think trampolines are dangerous as long as your children have responsible adult supervision.

You should be measuring the circumference of the finger, not the length. mg-jewelry.com/ringsizechart.html has a size chart.

Not sure how long her hair is, but one thing comes to mind. Use some virgin olive oil, squirt or pour some on each hair ball, work it through a little bit with your fingers or something with a pointed edge. If you need to add more, than you can do it. Put a shower cap over it, leaving the olive oil ...

Well i can understand what you are talking about but why don't you try in trampoline company where you get trampolines parth that for sure

Many trampoline stores are available on internet. Fun Spot Trampolines is one of them offers best trampoline deals.