For the Spreads, both of the calculations are correct. Just remember the $2 Nadex fee as well. (Some people like to add it into the mix)
Binaries are a little different. Basically you are asking the question… At expiration will the Indicative Price be higher (or lower if a short) than the Strike Price you have chosen.
For example purposes…
I believe the EUR/USD will remain under 1.2390. So I purchase a short contract. Since binaries are basically yes or no. At expiration you will either lose your initial investment or gain the sum of (100 - initial investment)
In this case, my initial investment was $65… If I am wrong and the market goes up. I will lose that $65 at expiration.
If I am correct, I will come away with a $35 profit if held until expiration (not including fees)
You can always sell them before expiration as well.
However it is STRONGLY recommended that you not hold binaries until expiration because they are all or nothing at expiration. If I have a $25 profit right before expiration… yet the market turns against me at the last moment, my $25 profit has now turned into the full $65 loss since I was greedy 
As for trying to make a profit. Both the Indicative price as well as time remaining will influence the price of a binary.
A trade that only has 20 minutes remaining will be closer to max price than a trade with 1 hour and 20 minutes remaining, if the direction is correct (of course if something like what has been going on in the US markets the past couple days happens… then this isnt always the case)
Taking a look at the trade, I can see that it has gone against me and is showing a greater loss. However, if the price were to remain at exactly where it is now… as more time passes, the trade would slowly start to show a profit. .
