Need help with Shrinkies

Hello ladies...

I am new to the board and I have a few questions about the shrinkie technique.

I am mixed and I have relaxed 3c hair type.  My hair is naturally curly, semi coarse, but i have been getting it relaxed for a while.  I want to do a sewin but for blending resons I want to do shrinkies in the front.

Is this safe for my hair type?  I am very hair conscious, I am growing it out so I dont want any setbacks in my growth progress.

Now with the shrinkies, they already have glue lined in them correct?  So all i would need is the shrinkies, threader, a dual sided heat wand and the remover right?  Would I need to pretip the hair?  And if I did could I use keratin glue to tip the hair?

I was going to purchase from shrinkies.net

thanks in advance