Questions about traveling to Egypt

Hello there! Me and my girlfriend are planning on a trip to Egypt! I would like to ask the following.
When is it best to visit Egypt?
Among Cairo, Luxor and Alexandria which one would you suggest and why?
How long a stay would you suggest?
Is it safe for just the two of us alone to visit Egypt?
How much money per day?
Are there any hostels and if yes are they worth checking?
In case we don't make it to Egypt, do you think Morocco is worth a visit?
Sorry for asking too much but I would highly appreciate it if you answered! We are discussing this some time now and we just started planning it!