Make sure y'er not naming the file with spaces. If there are spaces, 'twill cause FH to crash.
If y'er using GIMP, make sure that all the layers are compressed. Sometimes ye 'ave to copy all that's visible and place it on a clean "page". I 'ave to do this constantly b'cause FH doesn't recognize that I've already compressed it to one layer. This may also be an issue with photoshop, but I'm not certain since I don't ever use that program.
And to answer y'er last question, yes. If ye send all the correct files to someone else and they know how to, and do, place them in the correct places they can use the files themselves and make the map f'er ye.