Okay, lets go thru your list.
1) I really think loading up on two possibly organ damaging drugs is not a good idea. The Ibu will ruin your stomach, and the APAP your liver. CWE the pills
2) Tollerance builds extremely quickly with sustained daily use. I tend to use some kind of opiate almost every day.. 40-80mg of oxycodone barely touches the sides for me.
3) No, Opioid drugs are cross tollerant to a certain degree. If you become tollerant to codeine for instance, taking DHC you probably won't notice much difference in effect - its not that much stronger
4) It should increase the effects, but who can say - i'm not you
5) You should be fine, so long as you're not exceeding 4g of APAP a day.
6) It should. as both of these opiates use different enzymes in the metabolization process, codeine relies heavily on CYP2D6
7) No, it should also increase the effect.
8 ) Take some other drugs to counter-act those effects, i don't know how you're gonna stop the sorbitol shits. as its an osmotic laxative.
9) Damn straight, all opiates tend to cause this, lay awake, can't sleep itching balls. Take some benzos to counter-act that.
10) A little bit. try different routes of admin, DHC/Codeine are shit, seriously.
11) nfi, i dont smoke
12) I lost 22kg thanks to methadone and other opiates.
13) Not really... try some stronger opiates, like, oxy for instance.
14) grapefruit juice should potentiate, DLPA will too (DL-Phenylalanine)
15) CWE, grapefruit juice, DLPA... etc.
god im glad thats over, i hope my opinions help