thank you Amph,

for the already unconfirmed tx i have set a 10k satoshi, and the network propagation is 0%, so it didn't work. and yes, it's a little bit under 0.009 btc.
what will happen if will not be accepted by miners? and when? is there a time limit for tx to wait?

for a new similar tx do i have to set a 50k satoshi in order to be sure? if i use a sending Blockchain wallet is there available a "dynamic fee" option like for Electrum wallet? anyway, i suppose there is a formula to be applied, not a "question to miners / answer from them"?

thank you.