If it's emissions you are worried about, then no worries. It will pass.
Great brand chips are by Dinan, Turner/Jim Conforti, and AAtuning. You dont need to send in your ECU at all. A chip is the best first upgrade you can do. What i recomend is you buy a AA Tunign intake system. Call them up, tell them you want an intake and a chip and talk with them. Chancesa are they will have a chip perfectly made for their intake. They really do great testing to ensure you get the most power out any combination. Even better is you save up a little bit more, and order a Intake, exhaust and a custom mapped chip from them.
Also, if you are really smart you will get all 3, and make sure to run dyno tetss and spend time sending the chip back to them with all the info and they will do a great job and perfecting the chip.
Honestly, any GOOD BRAND chip will be a GREAT addition to your car. Dont just pick up an ebay chip I believe the ebay chips will add power, but you may suffer and not gain as much as you would wish.
A chip is a simple put in pull otu process. If you dont liek it, take it out and put in the original one. When you are talking about remappign your ECU and such nonsense I believe you may be reffering to the process related to the 1996+ cars. Luckily you have a OBDI system in your 1994.
As far as exhaust systems go, the Ansa sucks monkey dick. Sorry for the vulgarity but the Ansa exhaust, when tested with an intake, lost horsepower and gained about 2 lb/ft of torque. Thats right it lost horsepower. The tips ont he Ansa are supposed to look great, but its not worth the overpriced loss of power. If you want power out of an exhaust go with the AA Tunign one with a custom chip for it and an intake. Also for an exhaust consider Supersprint and UUC. If you can find a UUC TSE that would be awesome, but thye dont make them anymore. The UUC System U is also a really great exhaust and the new UUC RSC is supposed to be good but I havent yet seen any figures on how well it has worked.
And for future reference, if you posted this topic in the 3 Series (E36) section, you would have gotten at least a dozen responses much quicker.
Good Luck and post any more questions!
Oh, and by the way, Welcome to Bimmerwerkz.com! I hope you stay and enjoy!
Edit: God damnit I forgot to posts some websites for you www.aatuning.com www.bavauto.com www.turnermotorsport.com www.dinanbmw.com
All four of these sites are very well designed and can get you all the parts you are looking for. They are among my favorites