Those locked doors in Aleroth city is normal ... you can get in there after the start of Flames of Vengeance ... that seemless start after finishing the end battle of Ego Draconis part
The Hall of Echoes is, warning!, a point of NO return ! So be sure you solved all quests etc you wish to do and doing all battles in FF, Orobas Fjords and so on ! After Hall of Echoes FoV part starts without delay
If you've problems with the L28 archers ... me too, but after changing form Ranger Priest to a more full Priest style give me more time en room to survive !
For example :
using Hide in Shadows after summon my Ghost & Creature (fighter) ... I run to an archer and Blind or even better Charm him ! It makes a big difference for the outcome of each battle ! Adn if your Charm is higher (L3 or 4 I believe) you can Charm 2 enemies at once !
