Great Question Hoops. This is another factor aimed at draft strategy. Do you go with the 1 season guy this year who is out in 4 years or the guy who is just decent both? Well...it depends on what the rest of your roster contains...

and if you can afford that.
I tried to explain that in my #7 rule above but perhaps was not clear. You will be allowed to add/drop but only after the official draft to fill your roster. In your specific example...say you only have 16 eligible players..then you will draft your 7 and be allowed to add/drop 2 after everone else is done...vs. the 1 allowed by the league.