Yes, the grammar here is correct. :) Your question should have been "Is this correct grammar?" instead of "Is it right in grammar?" though. ;)

You should put in "to." "My advice is don't pay too much attention to marks." You always pay attention "to" something, never "on." :)

One would be correct. :) Once you have completed the book you can say "I read that book."

The sentence is okay and natural, as long as it is in proper context. Out of context it would be very odd and make no sense without a clear subject. :)

They have very similar meanings, but generally a "consequence" refers to a negative result, and "outcome" by itself can refer to either a positive or negative result. If you would like to give it a positive connotation you can also say "positive outcome." Hope this helps! :)

Should be "Is there anything I could do for you, other than to say thank you?" The comma isn't a big deal but it should be "other than" not either of the options you listed. :)

No, using arrive to would be grammatically incorrect. :)

Well to start with in most situations you won't need the "be" in "liable to" or "prone to" and "apt" usually isn't attached to either. If someone is "liable to" do something, it means there is a high chance they will do it or it is a very believable possibility. Example: "Jimmy is liable to skip work." This would make sense if Jimmy had a history of missing work or an event happened that day that would cause him to skip work. If someone is "prone to" something, it means that the thing they are prone to happens often or happens to them easily. Example: "Jimmy is prone to sudden illness." This would make sense if Jimmy was often suddenly sick, or Jimmy easily becomes sick. "Apt" has two meanings that you could be getting at. It could mean "appropriate or suitable in the circumstances" Example: "An apt decision" would be a decision that is appropriate or suitable in the circumstances of the situation. "The boss's decision to fire Jimmy was apt considering how prone he is to skipping work." The second meaning of apt is "having a tendency to do something," so a similar meaning to saying someone is "liable to" something. Example: "Jimmy was apt to forget to set his alarm." However it is worth noting that you rarely hear this usage, and as a native speaker it sounds weird to me and I would rather use a different word. I hope this helps you! ^_^