I'd use custom items to accomplish this. First is an item to allow your aquatic animal to walk:
Belt of Piscine Endowment
Aura faint transmutation; CL 5th
Slot belt; Price 30,000 gp; Weight 1 lb.
DESCRIPTION
When above water, this belt seems to be made of sharkskin. When below water, it seems to be made of the skin of a furry mammal.
When worn, this item allows aquatic creatures to grow legs and gain a land speed, exactly as the spell fins to feet.
CONSTRUCTION REQUIREMENTS
Craft Wondrous Item, fins to feet; Cost 15,000 gp.
Since all aquatic creatures either have a belt slot or a land speed (at least, all the ones I know of do), this works on all non-walking aquatic creatures. Before you can afford this item, you can use the Fins to Feet spell, which is a level 3 wizard, witch, and druid spell.
For the ability to breathe, there are a few options, depending on how much you want to stick to RAW.
First is a custom magic item of sea steed (18,000 GP). This is intended to allow land-based animal companions to work as sea-based animal companions, but it works just fine either way. This gives the animal the amphibious quality, allowing it to breathe on land as well as under water. This spell doesn't last long enough to make it practical as something to cast regularly before you gain access to the item.
Second is the Waterskin of Woe (80000 gp). This item lets you remove all the water from a creature, and "does not need to breathe, eat, drink or sleep and is immune to non-lethal damage." Since it doesn't specify what you no longer need to breathe, it should work on your shark just fine. The problem with it is that it deals 1 point on Constitution damage per day that it was used once you stop using it, and can only be used for a number of days equal to your Con score. However, there is no limit to the number of times you can use it per day, so you could easily turn it off at night, heal any Con damage with lesser restoration, and turn it back on while the aquatic creature holds its breath.
Third is the Necklace of Adaptation (9000 gp). There are a few problems with this as written. For one, it is a neck slot item, and the magic item slots for animals guidelines say that neither sharks nor octopi have neck slots. However, you might be able to make the argument that you could put it on a belt slot instead, possibly for a higher cost. Next, it specifically talks about creating a "shell of fresh air" around the user, which doesn't really help aquatic creatures. Again, I think the argument could be reasonably made to allow a shell of fresh (or salt, I guess) water to be used instead, if the item is made for aquatic creatures.
Fourth is a custom magic item of life bubble (56,000 gp). This effectively works like water wreathing, but it doesn't specify that it lets a creature breathe air, only that it lets a creature breathe comfortably. It actually creates a 1 inch shell of "tolerable living conditions", which could be fresh or salt water as easily as air. For a shark, it's probably moving water, which will likely be a tad inconvenient.
Since fins to feet is 3rd level, and life bubble is 4th level, you can have a land-based shark or octopus by 7th level for the cost of 4 spells per day. 2 castings of fins to feet will get you through an adventuring day, and 2 castings of life bubble will get you through the 24 hours that you need to keep your animal breathing. Since most aquatic creature have limited equipment slots, you will likely need to put two of these effects on the same item, likely a belt. This will cost the same as the added cost of the two effects, plus half the cost of the cheaper ability (or the new ability, if created in play).
IF you want to go the super-expensive route, you could also gate in a Personification of Fury every morning, since it has a special air breathing spell-like ability, which works like water breathing, but lets aquatic creatures breathe air.
Probably yes, a sorcerer with an Intelligence score of 2 yet possessing sufficient Charisma can still cast spells with verbal components
The GM can rule that a low-Intelligence sorcerer can't cast spells, but the game doesn't outright say such a sorcerer can't cast his spells. Therefore, ultimately, the GM must decide. That's because according to Components
A verbal component is a spoken incantation. To provide a verbal component, you must be able to speak in a strong voice.
While Pathfinder has several sets of rules for things called incantations (e.g. here, here), the term incantation as mentioned in Components is undefined, so the GM can then consult his favorite dictionary and use that definition of incantation to tell the sorcerer player No spellcasting for you.
Further, the GM may rule that the sorcerer's low Intelligence score makes him incapable of verbalizing at all, dropping the poor sorcerer back to the prelinguistic stage of language development.
But, assuming that the GM doesn't want to player to head off to the other room and play Smash Bros. until the sorcerer's Intelligence is at least 3 and that the player appreciates the challenge of role-playing, essentially, a dog with a built-in shotgun, the DM should permit the low-Intelligence sorcerer to cast spells.
Note that I would be very wary around a dog with a built-in shotgun, especially if that shotgun were reloaded automatically each time the dog wakes up from a long nap. I'd go to great lengths to keep that dog fed, happy, safe, and appropriately amused.
Because it's been referenced in several Comments, in Pathfinder's antecedent Dungeons and Dragons 3.5, under Monsters as Races it says
Creatures who have an Intelligence score of 2 or lower, who have no way to communicate, or who are so different from other PCs that they disrupt the campaign should not be used.
Then, later under Ability Scores for Monster PCs, it says
The separate table for [modifying a PC's] Intelligence [score when the PC is a monster] ensures that no PC ends up with an Intelligence score lower than 3. This is important, because creatures with an Intelligence score lower than 3 are not playable characters.
Neither artifact, so far as I can tell, appears in Pathfinder.
Best Answer
Whatever languages you can normally speak. Elementals can speak, so you can, too, unlike animals. There's no mention in Wild Shape or any of the elemental body spells about gaining additional languages.