once you graduate from the hero's guild there are 3 different quests you can do besides the wasp quest. it says that you need more renown to do the quests. I tried to get more renown and it still said i didnt have enough to do the quests. does anyone know if you can actually do these quest?

If you check through the thread index, and the last few pages there is a therad liek this. No you cannot do them.

To answer your question of why they are there, it has to do with a part of a hero competition where you would have to do more quests and be better than other heros that they took out.

i did them..... they stay there for a while afterwards... or am i wrong...

You cannot do them. Once you reach the renown level required, they disappear from the map table.