Learn English – “I would be available to attend an interview”

The difference is in the reference point of time where the speaker perceives him/herself to be.

I will do my homework by 6 p.m.

The time is sometime before 6pm, and the speaker is simply asserting an intention to do the homework before the stated time.

I will have done my homework by 6 p.m.

The time when this sentence is spoken is the same as before, but the speaker is moving the reference point to some time in the future after 6pm. Effectively s/he is saying that "When we next speak (at sometime after 6pm) to see what my homework status is, I will be able to say that I have done my homework".

The future perfect tense is useful when discussing something else that is to happen. For example

"Let's go to the cinema tonight. The movie starts at 7pm and it takes half an hour to get there. Can you come?"

"I think so. I will have done my homework by 6pm, which gives us half an hour to eat something before we need to leave. So yes, let's go."

Your sentence implies that your arrival at the airport is certain. However, "would be waiting" is conditional so it would require the first clause to be conditional too, for example an "if" statement:

If I were to arrive at the airport tomorrow, my whole family would be waiting for me.

If your arrival is certain, but it is your family's presence that is uncertain you would use "may" or "might" instead (these words are used pretty much interchangeably in modern English):

When I arrive at the airport tomorrow, my whole family might be waiting for me.