So I have a 99 eclipse spyders gs with the 4g64. I'm guessing I'd buy one designed for the gst or gsx since my battery is in the same spot unlike the 420a eclipses. I just want to confirm this before I buy one. Also I'm thinking of either getting the RRE bar or a DC sports bar, any recommendations be welcomed.

Pretty much. You get to treat it like a turbo car, but without the turbo if that makes any sense. Unlike the 420a, which is all weird. Lol

Its the same bar, you just turn it around.

^^Not always^^ I had the turbo model DCSports strut bar on my first spyder, but I always liked the non-turbo version more. So I bought the non-turbo version for my current spyder and it does fit, as long as I move the MDP sensor. Not a big deal since it does manage to clear my battery as well. I tried it turned around, and yes, it does fit, except when you shut the hood. It interferes with the hood closing properly, and you could just force it, since it's not by much, but who really wants to distort their hood?

OK, not sure for a Spyder n/t since you guys are the odd duck when it comes to aftermarket parts, but try to get the type that run along the firewall. DC cs-2 series look nice but personally I've never even felt any difference with the bar, front or rear, fwd or awd, as many have said, and before I dropped the battery I had an incident where my car just shut off on the highway after hitting a big bump and the bar cut the positive cable, so be forewarned. I have the DNA (Megan knockoff) bars on my fwd and buschur rear on my awd.
As we know by now, the best bar that will yield the best result is a one piece solid bar, non adjustable. If you're getting an adjustable set, might as well go with eBay since it's mostly asthetic anyway, not to mention one more thing you have to remove to work on your car. If you choose adjustable, just make sure you jack up the end your putting the bar on and tighten that sucker up.
For a fwd DSM I've noticed the biggest improvement in handling when I put in beefier front and rear sway bars (I have ST bars, but cheaper ones work just fine); to me it was a night and day difference.
Add to that a properly depowered rack and you will never look back. I almost fly off the road after driving my fwd and then drive my jeep or Tsi awd which both have power steering. I hate it.

I have a RM rear sway and noticed a positive improvement, granted the car had no rear sway bar before that. I'm just trying to get rid of some of the cowl shake and get the car as tight as possible. I want the RRE bar but they are a pain to order from. I'll try with them one more time and if I can't get it I'll go with the DC sports bar. Thanks for the help guys.