bitcoin is not the right blockchain to actually use at this moment.

Wrong. Bitcoin is the most secure ledger, and the one that you should be using.

I wrote already to GDax support after 2h30 and 3 hours but still no answer...

Stop spamming the support with bullshit.

What else can I do? Just wait I guess ...? How many more hours can it last ?

Wait until the network starts operating normally.

GDAX send the currency for free, I guess they pay the network fees by themselves?

Yes.

What is the risk ?

The risk is losing all of your money.