quick question:

if i want to activate both Cold Wave and E-Tel.
does the priority passed to my opponent after i activating Cold Wave.and if he didn't respond i can then chain E-Tel?
or I should activate both Cold Wave and E-Tel before passing the priority.
or I can't do it xD

You can activate both but like this:

Cold wave then your opponent may chain if he doesn't chain then you're able to chain e-tele to your cold wave.

Just like Sam said, after you activate Cold Wave, your opponent has the right to chain something. If he doesn't, you can chain your E-Tele to your Cold Wave. If he does, you can still chain the E-Tele to his card, EXCEPT if it has a higher spell speed (Spell Speed 3, Counter Traps. For example, Solemn Judgment). If it does, you can't chain E-Tele because it's spell speed is lower, and you can't chain a card to another card if it doesn't have the same or a higher spell speed.

i don't know but after u pass the priority, it should be the chain resolve if your opponent don't want to chain anything.

Question answered twice, topic locked

Just to add to what Yuri Bakura said. In the Main Phase, a chain will not resolve until both players agree they do not have any cards to activate. It will work like this:

Chain Link 1: Player A's Cold Wave.
Priority passed to Player B.
- Player B has no response.
Priority passed back to Player A
Chain Link 2: Player A's Emergency Teleport.
Priority passed to Player B.
- Player B has no response.
Priority passed back to Player A.
- Player A has no response.
---Both players agree to enter resolution by not responding---