Asynchronous call of several async functions and exception handling

Hi all,

may be the question will seem too advanced for a newbie like me, but I really want to write this program. I am asking for a good advice on how to implement the desired logic.

I have multiple classes, which implement the same interface

class MyClass1: IMyInterface //The same for MyClass2, MyClass3 etc.
{
//Many many properties and methods
async Task<MyResultObject> IMyInterface.FunctionAsync();
}

Now I create one instance of each class Instance1, Instance2, etc. 

Instancei=(IMyInterface)new MyClassi();

What I want to do is to asynchronously call the functions FunctionAsync() and process the results as they appear.

{
//Somewhere in constructor
List<IMyInterface> classList=new List<IMyInterface>();
classList.Add(Instance1);
classList.Add(Instance2);
//etc
Task<MyResultObject>[] taskList = new Task<MyResultObject>[classList.Count];
}


foreach(var ins in classList)
{
taskList[i]=ins.FunctionAsync();
taskList[i].ContinueWith((num, opt)=>{MyProcessFunction(num,opt);}i,null)
}

The questions are:

1. Will this work, or I'm doing something wrong?
2. How to handle exceptions, which throw the functions FunctionAsync()?
3. How to count the number of the finished tasks so that I can be sure that all tasks are completed and I can proceed further?

Thanks in advance.