For the first question I can suggest this block "Indicator moves within limits". This block is a little bit scary, but it's a block who can actually iterate through candles and check values for each candle. Or, in "Condition" when you are using custom indicators there are few extra options available... for example you can find the candle number at which the indicator is "visible" (meaning, its value is different than EMPTY_VALUE)
Zig Zag, I hate this indicator
Whatever I did for this indicator, I don't want to touch it anymore. I don't even know how this shit can be used, but anyway. In the indicators list you can find it, I have added few extra options on top of the original custom indicator that comes with MetaTrader. You can also import it as a custom indicator (in My Indicators) and use it like this... if you know how, because I really don't know 
