H.W.
I have posted this so many times the URL should be tattooed into my brain:
http://www.betterkidcare.psu.edu/AngelUnits/OneHour/Toile...
Because of his age, if he prefers the chair to the insert, start with that. My son was 3 yrs 3 months when he showed readiness, and needed to use the low potty for a while, just to get comfortable and have easy access. Sitting down is one easy step: having to put in the insert, move the stool, climb up, etc. is a lot more work.
I think the article posted will actually answer most of your questions. I have worked with children in preschool/toddler care/ nanny environments and have helped a great many children to use the toilet. When I used the toilet-learning methods instead of the traditional rewards, this process became much more straightforward and more long-lasting. I did find a few consistencies, and will briefly share them with you:
1. While we like the idea of rewards, they are often problematic in so many ways. Staying dry is the natural result of learning the body's cues, and I've found charts/M-n-M's and other goodies just complicate things.
2. Keep away from the Pull-Ups. These are "magical underpants" to children, who don't perceive them as a diaper. If you need a diaper, use a diaper. Kids get incredibly confused by pull-ups, and also very attached to them (all the cache of underwear without the work of using the toilet promptly). I've seen toilet learning significantly prolonged and riddled with power struggles because of this product. Kids just can't tell when they are wet, and there's no realistic result to learn from when they have accidents: wet pants are wonderfully informative for a toilet-learning child.
3. While we like to be polite, civilized parents, our tendency to ask a child if they need to go actually thwarts the learning process. Our children are at an age developmentally where A. they are inclined to answer "no" just because they can (two is the classic age for NO!) and B. They need to be directed. If we ask them "do you have to go", they are likely to say no, then when we insist they use it anyway, they are very likely to feel angry and disrespected because we had asked them for their assessment of their need and now we are over-riding it, which is subconciously absorbed as a 'no confidence' vote from us. In short: never ask, but always tell/invite the child to use the toilet, and regularly. (I have even had to tell 5 year olds to 'go use the bathroom, please'. They'll sometimes just wait and wait.)
3. Because you are wanting your son to be the author of this process (it's his process, right?;) ), if he only has the patience to sit for 30 seconds, just start with that. Sometimes a child will appreciate holding a book or small toy or being read a short story. I always say never more than a couple minutes, because this can also develop into a power struggle. You are introducing an opportunity for self-development, and the more autonomy your son has in this process, the more likely he will be to create longer-lasting successful results.
I've discovered, over the years, that the more parents try to control and insert themselves into a process which is really the *child's challenge*, the more frustrating the process becomes for everyone. By setting the stage well, providing objective support and feedback (either, "Oh, you made it to the potty and your underwear stayed dry" or "Oh, I see that your pants are wet. Looks like the pee came out before you got on the potty. Let's get changed and then we'll give it a try again soon.") and keeping your cool, that will keep the experience grounded and managable for everyone.
And stick with the cloth diapers for as long as you feel you need to. Cloth is fabulous, because kids can feel they are wet. You might find that when you look through the list for assessing readiness, your son may be interested but not 100% ready to take on all the activity involved in toileting. There's a reason we don't let a child practice a sport until they have all their appropriate equipment, and so it goes for readiness. If we start before they have all the skills, it will be more frustrating all-round and take just as long as if we'd waited for them to be completely ready.
H.