First the hernia..... Both of my girls, now 9.5 and almost 7 had umbilical hernias. My older daughter's closed up on it's own by the time she was 1. My younger daughter's did not and she had to have surgery to close it. Our dr. preferred that she have it done before starting Kindergarten, so the summer that she was 5 is when we had it done. I would guess that if your daughter is 14 mos. old and it hasn't closed yet, it probably won't on it's own. The surgery was outpatient and really wasn't a major ordeal.
Now for the BM problems. I really don't think the hernia is the cause of your daughter's bowel issues. My younger daughter never had any problems with BM's. My older daughter, however, did. But not until she was around 2 and the hernia had long closed up. Like another poster said, all the straining your daughter does could maybe aggravate the hernia, but it really isn't likely that the hernia is the cause of the problem.
At around 2.5, my daughter had a really big BM. It wasn't that it hurt her so much as the actual size of it that I think freaked her out. It clogged the toilet up, lol. After that, she began holding it in which in turn caused her problems. We tried prune juice, glycerin suppositories, Karo syrup, etc, but none of it worked. Eventually we saw a gastroenterologist. She put my daughter on Miralax (this was before you could get it OTC). She was on that for about a year and all has been fine ever since.
I would suggest talking to your ped and trying something to help soften up your daughter's BM's and make it easier for her to go before the pain and struggle gets too ingrained and she really starts fighting going. I had a former co-worker whose son was on Miralax until he was 10. I think the sooner you address the issue, the better for you and your daughter.
Good luck! :o)