a and b are both correct for an entry stop => http://manual.zorro-trader.com/buylong.htm. Look also for the grid trading example under "Tips & Tricks".

For modifying the entry price afterwards, use a trade function. Either set the "TradeEntryLimit" parameter to the new value, or check directly if the entry condition is met and then open the position immediately. => http://manual.zorro-trader.com/trade.htm