Taking the easy one first, the correct format for IRP notation is whatever is easier for you to read. It doesn't affect the operation of the program.

All of the IR signals above are recognizable as NEC1, but the two learned by the GC ir-learner aren't exactly correct. In case you don't know, NEC1 is the most prevalent IR protocol in use. In fact, NEC1 is used in more designs than all the other protocols put together. It is very well understood, and is documented by NEC. Pronto Hex is also well understood--there's a document on this site which explains it.

I downloaded GC's Convert utility and looked at its results. The Convert program does not handle the repeating aspect of NEC1 correctly in the Pronto Hex representation, neither converting to or from it. That's a little puzzling since the GC IR format (available in "GC-100 API Specification" at GC's site) is quite similar to the Pronto Hex format, except that the individual durations are given in decimal rather than hexadecimal notation, and a device address is included. The main difference is that Pronto Hex specifies the number of burst pairs that are 1) sent once, and 2) repeated. GC specifies the number of repeats, and the offset to the repeating burst pairs.

I took a shot at writing the NEC 1 Power On signal in GC format.
sendir,mod-addr:conn-addr,4,38000,2,67,343,172,21,22,21,22,21,22,21,22,21,22,21,22,21,22,21,65,21,22,21,
22,21,22,21,22,21,65,21,65,21,65,21,22,21,22,21,22,21,22,21,22,21,22,21,22,21,65,21,
65,21,65,21,65,21,65,21,65,21,65,21,65,21,22,21,22,21,1673,343,86,21,3732

Maybe you can try that (perhaps stripping out "sendir,").