Hi and welcome to the forums. First of all, there is a pinned thread about suggestions and bug reports, click here
. You may find some of your mentioned bugs there as well, but I'll give you a short answer for each aspect.
1) Do you talk about campaign mode when you are fighting the Nameless? If so, which difficulty setting do you use? You have to find different tactics to beat the Nameless. You are right, they have some strong units and towers but there is always a way to outbalance them.
2) Dragons and Shaikan upgrades are not available for balancing reasons. It would have made the game too easy on certain maps.
3) This is a known bug that happens often when you load a game, but after another reload the limit should be fine again. It should be fixed with the patch that is in work.
4) Same as 3) I guess.
Nightsong's sidequests are on Nordic's to-do-list as well.