>>845617Personally I have never used velcro toys but I'm sure you can google up some useful reviews.
As for quickly opening rope there are special knots designed to open easily but the fastest way is always to cut it. Plenty of safety guides actually recommend a special cutter used in climbing, I forget what it's called.
If you're tying the knots loosely and don't put her into acrobatic positions (which you shouldn't anyway as a beginner) then this really shouldn't be that much of a problem.
However there are always unpredictable issues, like sudden anxiety attacks, cramps, a fire breaking out or even diarrhea.
Maybe try looking into bondage tape, like used in this pic.
It's a special material that only adheres to itself, without glue. So you don't have to worry about pulling it off of skin or hair.