I really want to buy the deluxe Imperial physical edition but since I got a HDD instead of a cd drive I would like to ask if anyone can tell me if I can download the game digitally if I buy the physical edition (via some key or what have you).

I'm assuming that I can but I just want to be sure.

I don't have a definitive answer but I assume you can as well since by pre-ordering you will get to play 5 days early and I doubt that will involve getting a physical copy five days early.

Absolutely yes, you can download the game digitally if you buy the physical edition. After it becomes possible to. (presumably in mid-March)

And yes, the deluxe Imperial physical edition have 5 days early access

Supposedly the code for early access is on your receipt; so you might want to check that when you buy it.

But from what I've heard, the retail collectors edition is pretty much sold out everywhere.

yes