Q:

Would these processes be probable on this planet?

Background
This planet, located somewhere in the Andromeda galaxy, orbits a M5V star about 0.682764 AU away from its star. The planet  is volcanically active due to the gravitational field of the star, kind of like the deal with Io and Jupiter. The planet also has liquid water at the poles in underground pools and frozen and liquid overground pools, where the life is supposed to evolve on the planet. At the equator, there is also a valley that wraps around the entire planet, which forms from chemical weathering by acidic rain. The idea behind the acid rain is that the frequent volcanic eruptions create the sulfur, which combines with oxygen, creating sulfur dioxide, this then rises up into the upper atmosphere, which reacts with other chemicals that then precipitate down as acid rain.
Question
One of my questions is would water be able to form underground on this planet? Considering the distance to the star and would the volcanic activity make sense, considering an M5V type star is pretty cool and might not have the right composition to form a gravitational field of such magnitude that the planet becomes volcanically active.
And my final question, are the chemical processes described accurate? I'm pretty fresh to this whole "worldbuilding" thing (and chemistry, to a fair extent)

A:

Unpossible. 

orbits a M5V star about 0.682764 AU ... The planet is volcanically active due to the gravitational field of the star` 

Typical characteristics of M dwarfs put the mass of a M5V star at 14% of M☉. 
With a distance of 0.68AU, your planet will be gravitationally less attracted by its star than Earth is attracted by the Sun - more precisely, the intensity of the gravitational field of that star will be about 20% of the gravitational intensity the Earth experiences from the Sun. 
Since there's no tidal volcanism on the Earth caused by the Sun, the chances of volcanism on your planet caused by the tides are infinitesimal. The planet should have a humongous size for the gradient in the gravitational intensity between the closest point to the star and its farthest one to create the mantle/crust displacements so large that the tides will cause significant volcanism.

If you look into that 'red dwarf characteristics' table, you'll see the largest M-class red dwarf is 60% of solar mass. With a 0.68 AU, the attraction from its star will be slightly lower than Sun's attraction on Earth. Still no dice.

