I'll try to help you the best I can. Hopefully some S14 guys will jump in on this.
1) Relates to question 4. There is a plug that connects to the transmission called the O\D position sensor. This may be causing your issue with the O\D light coming on. This sensor connects to the transmission right in front of the rear mounting bracket. On the S13 we actually have one for 4th and 5th (O\D) gear. Since I do not know how speed limiting works on the S14 I can only assume this was removed so you are not reved limited at 5000 RPM in 5th gear. I removed my OD plug for this purpose. Heheh.
2) Get that code checked. If you looking at ECU codes here is a link to what they mean:
http://www.240sx.org/faq/artic...h.htmAlso to check the ECU codes via the dash is located here:
http://www.240sx.org/faq/articles/ecm_reset.htmI dont have a link for the OBD codes. Sorry.
3) How many times is the air bag light flashing? I can look it up in the service manual and try to narrow it down for you.
4) Addressed in question 1.
5) Do you notice any type of nervousness when driving? Somebody with frame knowledge would be best to answer this for you.
6) See #2.
7) Tried my best to find out about this O\D light. Sorry I came up short.