I need to buy a full set of acoustic strings for my Washburn. This is the first time I have ever needed to buy them (as I am pretty new to the guitar scene). Do I need to look for anything special or can I just walk in to a music store and grab a set of strings? Also roughly, about how much do they run in price? Thanks in advance!

I have an Epiphone SG G-400 and I have got it set up but haven’t replaced the strings yet. I’m looking at getting some Ernie Ball Regular Slinkies, are these good strings for playing Metallica-style rock? And will I need to get my guitar set up again, like will I need to change the intonation and will I get fret buzz from new strings?
Please include details and be specific.