Hondata

before getting hondata, is it a must that I convert to obd1, or can I run my stock ecu?

I have a 99 honda prelude.

If you have an OBD2 vehicle, you'll need to move to OBD1. The steps go something like this:

1) Buy preconfigured Hondata OBD1 ECU (typically a modded P28) from a Hondata dealer.
2) Unplug OEM OBD2 ECU, place on shelf/sell on eBay/use as paperweight
3) Plug in Hondata OBD1 ECU with OBD1-2 adapter harness (or use Hondata-modded OBD1 ECU that already has OBD2 plugs)

If I have bought a p72 from a 94 gsr... can I just buy the hondata program and have a authroized dealer install it in my area, or do I need to send ecu into hondata

I plan on using the s200 program

An authorized dealer should be able to make the modifications to the ECU. A good dealer will be a one-stop shop.