The issue with simply putting the thrust levers full forward to command a go-around on any Boeing is that - unlike Airbus - the thrust lever position always determines the thrust command to the engine. So putting the thrust levers to the firewall will give you max TO thrust for those conditions
Yes, until you take the hand pressure off the levers. Depending on the A/T mode the levers(thrust) may well retard back to a previous setting will it not?