Not sure if this is the right category to put this - there's a character who's 18 years old and is portrayed to potentially have romantic feelings for characters 12-13 in age.

Characters kiss occasionally, but not graphically.

There is quite a lot of cartoon blood in the show, including a couple of murders, and a car accident.

Someone gets stabbed in S4E60, it's not TOO graphic. Someone gets shot in S5E11, it's a little graphic. Someone gets badly stabbed in S6E11, it's pretty graphic for almost the whole episode. There's also small moments littered through the show with blood, like cuts and stuff. However, ALL of this is cartoon blood, so if you're okay with seeing graphic cartoon blood but not graphic real blood then this show will be absolutely fine for you.

Occasional use of "hell" or "crap" but no major swear words.

The google translate episodes often contain words like "ass", "vagina", "penis", "seducing", "porn", "rape", and "condom", (S6 onwards, so if you watch the ones before S6 there's a lot less of this) as well as a couple of other swears words, the seven words specifically mentioned are used in the latest inside jokes specials (inside jokes 5 onwards, so if you watch the first four there's none of this), however NONE of these are used AT ALL in the main episodes so if you watch the main episodes don't worry about any of this as it will not be there.

Amy - one of the lead's mother - is an alcoholic and neglects her children due to this.

Alcoholism is mentioned quite a bit. A couple of times "vodka" is mentioned. Or there's an empty bottle of alcohol somewhere.

There are quote a lot of intense scenes in the series when the past is brought up. There are a lot of deep conversations, often revolving around death or crimes.

From Season 7 onwards suicide is mentioned sparingly, and someone does try to commit suicide on multiple occasions (spaced quite far apart though).