I'm planning to buy an 2500k and overclocking it in the future.
Right now i have the Arctic Freezer 13 but I was wondering if it will do the trick as I'm planning to overclock from 4.1 ghz to 4.4 ghz.
As the price difference is only $4 between those two, I'd personally go with the Evo. I currently have the Hyper 212+ (non-evo) on my 2500k with a 4.3 Ghz overclock, and my max load temps are between 49-51 which is very safe. 4.5 Ghz should involve little -> no voltage tweaking so your temperatures assuming you have decent airflow in your case should be around mine.
EDIT: I completely forgot you said that you had a Arctic Freezer 13, that should be fine for a 4.5 Ghz overclock in my opinion, the design is fairly similar to the Cooler Masters listed above.
If you plug them into slots 2 and 4, it'd be the same as putting them in the 1st and 3rd slot. I have my Ripjaws in the 2nd and 4th slots, and there's no performance decrease.
i have a 2500k @ 4.5 with a Hyper 212 EVO with the stock fan and it keeps it nice and cool. Every game game except BF3 keeps the temps in the mid to low 40's. I've seen my temps go to 60c while playing BF3.
I use Corsair Vengeance LP Memory fits under the heat sink.