2) Everyone should understand that the difficulty of obtaining the base weapon is clearly Mythic (hardest) - Relic - Empy (easiest). I'd personally certainly go for the Mythic, and anyone who cares about any job with a decent Mythic would probably be well served to do the same. But in some circumstances I can see why a person might not care to select a Mythic for a rank 1 prize. Maybe you only care to play jobs that have a relatively crappy Mythic - NIN THF RNG BRD COR etc.
You could take the cash and pay people to get you a level 90 Empy and still have 80% of it left over.
Yeah, that's pretty hard to argue against. Especially for Relics, if you really wanted one you could take the gil prize and very quickly buy ALL of the currency to get a lv75 weapon, AND all/most of the Umbral Marrows to get it to 99. I'd be disgusted with someone who couldn't be bothered to do the fairly simply 75-95 Relic trials.
While an Empy would take a bit more time just to get through the NM phases and get all the pops/items you need, you could totally merc all of the lv80/85/90 items and have plenty of money left over to buy Heavy Metal Plates and Riftdross/cinders.