Okay going through the list here.
No. Dodging will not stop if you keep holding the button.
No. You can hold down the button to keep in dodge mode.
No. You do not need to be locked on or facing the enemy to dodge.
From what I can tell there aren't any undodgeable attacks (unsure on this fact)
Depending on your weapon you may not be able to dodge for a short bit after attack. Larger weapons are prone to this such as the great swords.
From what I have seen you can tell you are in dodge mode when your character walks around slower and seems to hunch over a little bit like if he was holding a shield.
I am pretty sure your problem is with larger groups of enemies, or enemies with large attack arcs. From my observation, while you are in dodge mode, you are not immune to being attacked. If enemies gang up on you while you are dodging other attacks you can still be hit. Same goes with enemies with larger attack arcs, you may get off the dodge, but an arc of an attack can still hit you. Your best bet for these situations is to simply dodge roll out of the area and not hold your dodge button.
Sooo...I just caught it finally last night...it is in the Vesperpoo, andl you will need to first get plenty of Dragon's Beard fishing line, the reel and rod from the shop next to that spot (which are like 18000 gil combined), and a green lure which I'll be honest I don't remember the name of and I'm nowhere near my game at the moment, sorry...but you may also want to be at level 7 skill level for fishing as well, since you get linger lasting line.
The key is you need to camp at the haven near that, and when you do there will be a cut scene where Gladio will ask you in the middle of the night like a weirdo if you wanna wake up at the ass crack of dawn to catch that legendary fish...it then becomes a tour, and i believe you will need to also clear the entire vesperpool before it will engage you...take note, it doesn't appear on the HUD, and you will simply have to keep casting til it takes interest in your lure, and then entice it to bite...
After that, once you've got him hooked, you really really REALLY need to be patient...it took me about 4 tries, and I had been fishing for almost 3 hrs to get my skill up, so I was kind of in a groove by that point...his stamina is off the charts and you can only reel when he stops struggling, so you'll need to pay special attention to line tension and also catch the jumps to, if you know what I mean...his "attack" will deplete your line very quickly if you don't just go with the flow and take your time...get ready for 20 minutes of battle fishing, and good luck!
Ps-I tried to upload the photo I took so you could see what your catch would be but it wasn't working...it's gratifying if you like a challenge though
Best Answer
Prompto has 10 Photo Skills, 5 of which are filters. The Official Guide does not list any additional filters, however a few exist. I haven't personally been able to obtain more than the three you've already acquired.
Filters:
Additional filters:
These can be adjusted in the Archives Menu under Filters. The player can set them to be used:
.