I lived in Tahoe and skied Squaw everyday for half a decade, but I left more than 10 years ago. I don't have up to date information, but I will say that as far as areas off KT go Headwall is insane. The Light Towers, North Bowl and the slot are awesome. You can also access all of Cornice II. One of my favorite laps was to hit the Slot and then cut skier's right into CII and ski classic chute or hourglass. Lots of good lines in the whole Headwall area even when there is no new snow. Light Towers is one of my favorite spots on a pow day. North Bowl can get great windbuff. Granite is also really fun. The peak is insane, and the chair has lots of fun stuff too. Siberia ridge is one of the really great places to huck on a pow day and the Palisades are awesome if conditions are good. Mainline Pocket is another great hike. You can hike Palisades or the Pocket without new snow and sometimes get good turns, although I usually waited for new snow to hike. Silverado is awesome, some of the best terrain on the mountain. It has low elevation and the chair is slow, so I rarely went there unless there was powder, but on a pow day it was one of my favorites. Broken Arrow has some cool lines too, although it gets sunbaked pretty early. That can be fun though, when it has not snowed in a while you can sometimes get good slush turns down Tower 16 in January because of the direction if faces. Squaw has lots of different exposure, so somewhere will probably be slushy in February while somewhere else will have wintery snow. I used to lap the KT alternates all morning and early afternoon some days, then go over and hit Rock Garden when it softens up. You did not ask about KT, but KT has tons of good terrain as I'm sure you know. Solitude is also a fun area with lots of 5-15 foot hits, it is underrated and rarely crowded. The bottom line is that Squaw has tons of sick terrain, so enjoy. I ski Mammoth 35-40 days a year now, and while I love Mammoth I do miss Squaw. I would ski Squaw over Mammoth given the choice, although it does depend on the season. In a bad season I would take Mammoth, but otherwise I like Squaw. February can be a great month, it can go either way. But if the season is average the base should be good when you go. If I had my choice I would probably go in March, spring turns or pow, but February can be a great month. It just depends, I saw some big February storms when I lived there.
Alpine is one of the most underrated mountains in North America. It is very steep and has lots of great hikeable terrain. Alpine blows Vail's doors off steepness wise, put it that way.
Have fun. I have not lived there in a while, so I can't tell you about night life, but I would concentrate on skiing, you can party anywhere.