Ufffffffffff.

1) I had two wizards and during the battle in the crypt one of them died. However I completed the task by killing that creature and went back for reward. Only wizard that was alive got experience and got reward.
The other wizard now cannot advance further in the guild since he was not "present" during the bad guy execution
2) Macdawa cannot take my toad potions. I am using "Use/Give" but there is no way?!

3) The guy that I met near the Serpent Temple should have some key to give me. I talked to him but I didn't get any key. Now is too late since I have almost completed the tample but still I have one lock near the Monkey Room to unlock?!

Sorry, that's the way these games go. Not a bug (although there are some). Check some of the older clues at this site to help yourself. When someone dies, for example, they lose credit for the quest you do while they are dead. In this game, once you miss an opportunity it can be gone for good. DWB makes these games hard, he expects us to start over if we miss too much. Part of the spirit of being careful I guess......Save early and often (and use multiple saves all the way thru!)