I'd like to bump this thread and add more info:
But there were gaps that I'd like to touch upon and ask for help from others on the topics. So, here goes:
Pedals:
Pedals are very important on the track. They are not only tied to your acceleration, but your braking.
If you have quality road (not MTB) pedals on your road bike (like LOOK, Shimano SPD-SL, Speedplay Zero) then they should be fine.
If you don't, you will need to buy some as most entry level track bikes do not come with pedals. Some that I recommend are the Shimano R540 (approximately 40USD). You can go up from there if you like.
Be weary of buying really, really old used pedals that may have worn out retention systems.
MTB/CX pedals are desinged for rapid entry and exit as the rider is on/off the bike frequently during a ride. They are also designed to shed mud. These are not features that you will take advantage of on the track. Plus, if you pull out of your pedal, you will have to pedal one-legged till you slow down enough to get the foot back on.
Shoes:
Cycling shoes are like running or basketball shoes, if you want, you can spend $300/pair. But, an $80 will perform just as well.
If you don't know your size, go to a shop and try them on. For years, I rode size 47 shoes when I was actually a size 46...that's because I'm an idiot.
Clothing:
Cycling Kits are EXPENSIVE. You do not need to buy a $100 pair of shorts and a $100 jersey in order to ride. Just buy some quality shorts and mate it with a snug-fitting or compression dri-fit type Nike or Under Armor shirt. Those are around $25 and can be easily found. You don't need jersey pockets because carrying things in your pocket on the track shouldn't be allowed any way. Plus, you are never more than a few yards from your gear bag in the infield.
Buy the shorts with suspenders. They keep the shorts from sliding down. Trust me, you'll want these over the other type. Stay away from gel padding. To me these feel like a soggy diaper.
Skinsuits work, but are also expensive. Cycling Shorts + Nike/UnderArmor compression top is a "Poor Man's Skinsuit"...and much easier to get in and out of
Cycling socks are pricey. Running socks are not. They are pretty much the same thing. I've even used long soccer socks (long to allow for shin guards to be inserted) as my legwarmers
Helmets
A basic road helmet is fine. They are around 60USD. For the track, a skate/bmx helmet (30USD) is also fine and it weighs the same as a road helmet, it's just not as ventilated. But, track events are short, so you won't have it on for hours, only minutes.
Anybody got anything else?