Can Anyone Please Offer Clarification on the Roman Catholic Churches definition of Suicide?

Can Anyone Please Offer Clarification on the

Roman Catholic Churches

definition of Suicide?

As a Catholic, it is a very entrenched part of our religion that suicide is a “Mortal Sin”, To some the Ultimate Mortal Sin.

Obviously slitting your wrist in a fit of depression is Suicide!

But I have questions about various grey areas, and whether they count as Suicide (from my religion’s perspective,)

Would any of the below Still count as the Mortal Sin of Suicide?

One:

Self-neglect:

Would smoking, over drinking and not exercising to the point where you know this continued behaviour will kill you! Despite clear professional warnings.

While self-destructive, is this Suicide?

Two:

Self Sacrifice:

Is throwing yourself on a grenade (fugitively of literally) to save others, when you know there is no way of surviving the action count as suicide?

Three :

Accepting Circumstances:

If you have a horrible sickness with only million to one shot of winning so you decide to refuse further treatment,

Or are stranded n the wilderness with a broken leg with virtually no chance of being found,

Is acceptance and refusing to keep struggling suicide?

Is this act of surrender to Math a form of suicide?

Four (a):

Extreme Pacifism (immediate event):

If you are in a situation where you have to choose to kill an attacker to survive, But you choose to be killed rather than choosing to take a Human life?

Is this suicide?

An even greater question, which out of the two is the greater sin? Suicide OR Breaking the “Thou Shall Not Kill” law?

Four (B):

Extreme Pacifism (Tactical):

If you are in a situation where you know for sure you will be attacked and because of their physical or numeral superiority, you would have absolutely no chance of surviving.

(Obviously, there is no an option in this scenario to either run or negotiate.)  

Is choosing to Die rather than making some sort of pre-emptive strike to survive count as suicide?

Is this suicide?

An even greater question, which out of the two which is the greater sin?

Suicide OR Breaking the “Thou Shall Not Kill” law not just in the heat of the moment (as for version “a” above) but as a cold calculated decision?

Can someone please answer in the comments below,

(Sighting qualifications, source material and papal law or president, NOT just your personal opinion.)

I am also curious what the rulings and laws of other faiths might be in the above examples in order to compare philosophies.