The Stain: V1: Bloodstain

Full Summary:
The Stain is a Paranormal fiction novel that centers around Ava, a twenty-four year old girl who has been seeing spirits all her life. These "Visitors" have caused her much troubles, being kicked out of her family's home, ending up homeless, antisocial mindset and deep set paranoia.
Ava is a girl who has given up hope, but when a spiritual war breaks out on the other side of the veil and uses the world of the living as a battle ground and it's humans as pawns, Ava discovers the spirits are coming after her to use her as a weapon.
The shy and insecure girl learns that she has hidden abilities within her, that can be used to destroy.
She joins with a mysterious and troubled spirit with complete lack of emotions named Silas, who teaches her to use her gifts to fight to stop the war.
Over time she begins to wonder if Silas is the safest person to trust when she finds out he has many dark secrets that she would have rather not known about.
Quickly, Ava is sucked into a whirlpool of spiritual war, demonic clans, and kinetic abilities. She must learn to channel her fears and anxieties to unlock the hidden strength within her and understand who she really is.

This story contains a lot of more sensitive subjects, such as:
Possession, Mentions of Murder and Homicide, Mentions of sexual abuse and sexual assault, physical abuse, torture, blood, gore, some adult themes, and violence.

Questions and Author related notes:

I'm still working on some of the basics of writing, trying to learn more about paragraphing, comma use, and correct phasing for easy reading. I would like feedback and constructive critiques on these subjects.
I am also working on character and plot development and adding thrill, pacing, and tension to the novel. Feedback and critiques on this would be helpful as well.
I am trying to work on "Show and Tell," describing the character's feelings through actions, rather than always just saying their emotions or thoughts. Feedback on this would be great.

Other Questions:

So far, what do you think about the story and characters so far? Should anything be changed or altered in your opinion?

How was the paragraphing and sentences? Should they have been longer/more detailed or shorter/more spaced?

Please point out any grammar or punctuation mistakes.

Also point out any words that I have used too much and should change.

Should I add more setting detail? More physical expression? More thoughts?