wow, i like most all your ideas, here is my take:
1) Buildings that we can enter.
this engen uses the bulkey "instance portal system" that transports you to one of two places, eather a town( any ware on the map you can click and go ) or a instance ( any ware you go that you are alone or alone with your party) that makes it difficualt ( at least in my point of view, maby im totaly wrong ) to make a building to enter that is not on the map and is not an instance. but over all i totaly agree and hope that they get to these soon.
2) A more complete weather system... With Snow falling, Rain, Thunder, Wind, Cycle of day/night. I know that some area have some kind of weather, but it would be very nice to have something more complete/random.
i think they might have the same problem with the engen, but hopefully the will get to it soon ( i think i posted on this a while ago ). but a way to implament it might be as a
spell, or a
hex
b) Bards - We already have the /drums, /guitar, /violin, /flute emotes...
why about putting those to some great use? Perhaps with enchanted music?
i was thinking about this too, ( befor you posted, so i get all the credet

) if they implement them they would have to make shure they are diffrent then the
mesmar class, this might be implemented like the dnd way, such as the "jack of all traids way", or just trail and error.
5) More variety of fauna. More birds, fishes, land animals.
i like this idea, but most of all i would like to see the world interact with in its self. such as birds fishing, or sharks eating minnos, even if its not a "real" eco-system just to see it in motion would be great.
6) Sickness when traveling in cold areas... Especially if you don't put winter clothes on... ^_^
i like this idea, perhaps not just even colds ( witch i might add, can be cought any time of the year

, but flus, or heat strokes, perhaps. but that would mean, lowering the cost of fur, first.
7) defending the fort
i like the idea of massive battles, how about a town that is constantly being attacked. just throwing this out.