1: Yes. I must be awake for at least 20 hours to sleep well, otherwise it can take a few hours of trying. But if I fail (usually), I must wait another few hours, and I'm left feeling slightly nauseated, very bored, and a little sick of my bed and bedroom. For several reasons, I wake up in the evening and fall asleep late morning more often than not.
2. No, my drug use didn't cause my insomnia. I was frequently staying up at night before I started, but it still had a large impact on my sleep. I now have more trouble staying asleep when I wake up mid-night.
I consider Cannabis Indica to be a poor sleep aid, and Cannabis Sativa prevents me from sleeping more than oral speed does. As a daily smoker, I rarely remember my dreams, but they're always beyond strange. Cannabis can make me tired and it made my dreams more vivid but sleep less deep. More often than not, I wake up feeling tired, especially if I smoke to sleep.
Cannabis has negatively affected my sleeping, but in a relatively mild way.
Alcohol is a pretty bad sleep aid. One or two beers is nice but getting drunk or abusing it made sleep more difficult for me. Benzodiazepines and related drugs are generally good sleep aids. They are my favourite class for sleep. Since I find significant recreational value in zopiclone, it's no longer effective as a sleep aid. Lorazepam is more boring and can help at high doses. A plus is that the benzo "crash" is extremely easy to handle. A minus is that benzo tolerance is a bitch. A REAL bitch. Don't we know it...

Reducing from roughly 5-10 to 3-6 benzo and Z pills per day has made sleep more difficult, and long-term I have a bad feeling about them.
Diphenhydramine (A.K.A. Benadryl) helps me sleep. Lately, a single benadryl has helped me sleep, but higher doses shorten my fuse more than alcohol and make me feel like shit the next morning. It also lasts too long for me and produces distinct nightmares. There is usually more of a crash and hangover feeling than with benzos. It's a very decent sleep aid (and keeps me asleep), BUT having used high doses (up to 600mg), I now find it quite disturbing. It's a very nightmarish hallucinogen at high doses and feels very poison-like. Yes, deliriants have helped me sleep. I once took 20 dramamine tablets when I was young, inexperienced, and stupid. Since then, especially in the first two months, sleeping has been easier but scarier. Dimenhydrinate (dramamine) completely changed the way I slept, and dreamt, for a while.
5-HTP and melatonin have helped me sleep in subtle ways.
There was a time when I used cigarettes to help me sleep, but they are a little less than top-class sleep aids. It ranks higher than alcohol though.
3.
I was prescribed a low dose of Ativan (lorazepam) for sleep when I was a child.
As an addict, I always end the night with one to three zopiclones and lorazepams, and often add cigarettes, a few beers, and 1-15 benadryls (six is my limit before the druggie in me takes over). To spice up the mix, I usually add a good amount of Indica. I occasionally take Prazosin (lowers blood pressure), which reduces the required amount of pills by up to 1/3.
I may have answered more than you asked for but there you go.