The immediate issue I see is Double Cast - this is stealing form the RDM's identity. The ability to use both white and black magic and using doublecast to make up for the lack of raw power is the whole reason Red Mage is worth investing in when it shows up in most of its appearances. You're asking for speed casting, the signature of RDM, for a power caster like WHM. It makes very little sense for an MMO - the fact that you could give other mages doublecast in games like FF5 and FFTA are why Red Mage became train-and-dump in those games. It'd be bad design for 14.

Also... why buffs? Like, we WHMs are stupid strong healers. Those suggestions are complete overkill.

Just give me a water spell that I can juggle between Aeroes and Stone spells and I'll be happy since it completes the druid trio.