Regarding question #1, there are a lot of low limit players who like to see the turn with their overcards because it's "cheap". It's important to identify them and continue betting the turn against them.

I disagree with a lot of what Derk said, to some extent. But it's 4:44 AM and I'm on my phone in my bed, so I'll be more specific later.

That doesn't really disagree with what I'm saying. Like I said, a lot of people will want to stick around for the turn and may give it up then. As far as cold calling, you neglect to consider the context in which he's asking the question. He is a beginner to limit so his post flop play isn't very refined yet. Recommending that a beginner cold call with A8s is stupid. Also against a CO who is prone to stealing it can be better to reraise, but these are subtleties that he'll pick up over time.