MP is actually fun when people know what they're doing. We just destroyed Titan with great synergy between chars, supports, healing, etc. Good stuff
Yeah, she's a bitch. Just keep trying until you manage to beat hear, that's what I did lol
Save your mythril for XIV, yeah, if you manage to get a couple of good relics your performance will improve drastically.
Now try to craft Curaga/Curaja, Protectga, Shellga and some -ga spells (I recommend blizzard and thunder) until you get enough orbs for their -ja counterparts. Ruinga is good for farming too, yeah. Also some spellblade abilities to complement your elemental weaknesses arsenal. Then start to craft the breakdowns and aim to make your first 5* ability Full break. Lifesiphon is also crucial for the more difficult bosses, right now don't worry too much but keep it in mind.
Run the normal dungeons and elite ones when you can, reach as far as you can in the weekly events and don't bother much with the dailies until you have mastered all the normal and elite dungeons. Really, it's not worthy at your level of play, it's better to get more stamina, mythril and the normal drops than run dailies. You can of course run some to change the pace and get those first completed mythrils.
Don't worry and go slowly, in a month or so you'll start to be able to do the more difficult content, but this game is a marathon, you can't go very fast unless you whale like crazy.