I am new to the game, and somewhat confused. I searched the forums, and google, but couldn't really find the answer to my question. My friends and I bought the core set a few weeks ago and are looking to expand. Are confusion comes from not knowing what to buy next.

We see that some sets are labled as reprtins, and not sure what that would mean for us. From what I understand some of the older sets don't come with as many cards, but I am not really sure. I don't want to buy something that is going to be considered out of date, but maybe then it really doesn't matter? How does this whole reprint thing work?

Sorry about the grammatical errors. I accidently published without looking over it. Can’t seem to find a way to edit it.

Here is a list that I put together for one of my friends when he asked a similar question:
Big:
Core Set- 4 decks for Lannister, Baratheon, Stark, Targaryen- All cards x1

Medium:
Deluxe Expansions for every house- All cards x3
Kings of the Sea (Greyjoy)
Princes of the Sun (Martell)
Lords of Winter (Stark)
Kings of the Storm (Baratheon)
Queen of Dragons (Targaryen)
Lions of the Rock (Lannister)

Small:
Chapter Packs- released ~monthly.

A CLASH OF ARMS CYCLE- Black-bordered, 40-cards (So 3x of some cards, 1x of some cards- you will need 3x of each pack to have a play set)
War of the Five Kings
Ancient Enemies
Sacred Bonds
Epic Battles
Battle of Ruby Ford
Calling the Banners

A TIME FOR RAVENS CYCLE- First WB chapter pack (all the rest are WB too). Originally printed in 40-card format, now reprinted in 60 card format.

Here is how to tell if it's the old or new version (I'm not sure if it says on the box or not):

Front of 40-card version

Front of 60-card version
A Song of Summer
The Winds of Winter
A Change of Seasons
The Raven's Song
Refugees of War
Scattered Armies

KING'S LANDING CYCLE- Exactly the same as A Time For Ravens Cycle, originally 40, now 60.
Front of 40-card version
Front of 60-card version
You can see that the picture is the same, but they re-did the boxes to look more like current CP boxes.
City of Secrets
A Time of Trials
Tower of the Hand
Tales of the Red Keep
Secrets and Spies
The Battle of Blackwater Bay

DEFENDERS OF THE NORTH CYCLE- Exactly the same as King's Landing Cycle, originally 40, now 60.
Old version
New version
Wolves of the North
Beyond the Wall
A Sword in the Darkness
The Wildling Horde
A King in the North
Return of the Others

BROTHERHOOD WITHOUT BANNERS CYCLE- This is the first cycle that FFG made ONLY in 60-card format, so you can safely pick them up without having to check if you are getting a playset
Illyrio's Gift
Rituals of R'hllor
Mountains of the Moon
A Song of Silents
Of Snakes and Sand
Dreadfort Betrayal

SECRETS OF OLDTOWN CYCLE- All 60 cards
Gates of the Citadel
Forging the Chain
Called by the Conclave
The Isle of Ravens
Mask of the Archmaester
Here to Serve

A TALE OF CHAMPIONS CYCLE- All 60 cards
Tourney for the Hand
The Grand Melee
On Dangerous Ground
Where Loyalty Lies
Trial By Combat
A Poisoned Spear

BEYOND THE NARROW SEA CYCLE- All 60 cards, this is the most recent cycle so it is not yet completed.
Valar Morghulis
Valar Dohaeris

Hmm, apparently the links didn't transfer well, but you can copy/paste them into a browser to see what the different looks are between the old versions (which you will need multiple copies of for a full play set) and the new versions (which will give you a full play set in each pack).

Medium:

Deluxe Expansions for every house
Kings of the Sea (Greyjoy) originally all x1, now x3
Princes of the Sun (Martell) originally all x2, now x3
From this point, all Expansions have all cards x3
Lords of Winter (Stark)
Kings of the Storm (Baratheon)
Queen of Dragons (Targaryen)
Lions of the Rock (Lannister)

The old boxes are probably completely out of stock, but you might still find them on ebay and such.