1. Pee pads are the easiest. These ones are probably the best in terms of price/quality. My friends and I all swear by them:
http://www.amazon.com/All-absorb-Training-100-count-22-inch-23-inch/dp/B00EI673B6/ref=sr_1_3?ie=UTF8&qid=1451755743&sr=8-3&keywords=pee+pads Watch out for some other brands because the pee will leak through and create a bigger mess. Some dogs will also tear up the pads (thank god mine doesn't) - I'll let others chime in on this! Never tried litter.
They absorb odor pretty well (from pee) so I don't have issues. If your dog poop is solid, you can pick that up, flush it, and continue to use the pad for pee (assuming there's not a ton on there). I use 1 pad/day when I have work.
2. I don't know why I would train my dog to tell me that if I am not home... how would this work? Or are you asking how to have the dog hold everything when you're not at home? The easiest method for this is crate training, since the dog (usually) won't soil their bed. I only do this if I am gone 2-4 hours.
In general potty training, my dog began to associate the door with going outside/peeing/pooping. So she now waits by the door if she wants to go. Also, EVERY TIME she would pee outside, I would say "good peepee" and give her a treat. Same for if she went potty ("good potty"). She learned the difference between the two in a couple of weeks, and now I can ask her, "do you want to go potty?" or "do you want to go peepee?" and she will lick my face for either. And she does know the difference which is crazy to me. And if she doesn't want to do either, she doesn't lick my face and walks away. Lol.
3. Diaper genie is the easiest. My friend has one and swears by it. I don't have one so I throw poop in the toilet, and if I throw the pad in the trash it smells :( I live in a condo with a community garbage down the way, so most of the time I just suck it up and walk all the way down to toss the pad.