Well..
That all depends on the snake itself and your level of comfort in handling the snake. I found that the more assertive I was in my snake handling, the less likelihood of myself getting bitten. They seem to pick up on the subtleties of your fear and emotions and use it to their advantage. When I first got into snakes, I was leary of being bitten, and was a little more jumping in my handling, and was subsequently bitten a few times. But once I took control of the situation and the snake, I didn't have a problem. I just reach in there and grab em before they know whats going on or given time to get defensive.
As for the pain, I think the looks are worse than the feel honestly. I've had cat scratches that hurt worse, and I still rough house with my cats. Its more startling than anything. But if you do get bitten and he latches on good, don't pull him off as it can rip his teeth out. What works for me is putting his head under running water, and he'll quickly let go.
Most corns I have for myself and have handled have been very well temprered. Hatchlings and younger individuals are more likely to strike and bite and be pains in the rear. But through regular handling quickly settle down for the most part. Although there are those that never settle and persist in acting like a cobra their entire lives.
As for evading, my hatchlings can be tricky trying to catch at times. But most of the time, they're in or under their hides all curled up and are easy to grab.
As for guinea pigs, I had those for years. And you just need to make it a habit to force them to be handleable. You pick em up and hold them in your arms like you would hold a cat, don't dangle them as they don't feel comfortable floating in midair and then pet them. Afterwards, a piece of sweet pepper as a treat. They'll be welcoming being handled from then on.
I hope that helps some. Welcome to the hobby, it's addictive. =D