Everyone is different in how they interpret these, but I take them as follows.
"Eat to your meter" means don't eat foods that seem to consistently cause highs. For me, I go high (and low) for things other than food. So sometimes I'll be high after eating one time, but not the next, even though it's the same food. So I interpret this to mean that I don't eat foods if they cause highs most of the time, even if I happen to be fine one some occasions. For me, anything that puts me into the teens (above about 250) is too high. I find it hard not to spike over 11 (200) when I eat any food, if I test at say one hour, so I don't really consider that high, even though others definitely would.
Many here refrain from eating if they are high, which is why they might say they "can't eat" if they're high. For me, I will try to delay a meal if I'm in the double digits (over about 180) until I've come down a bit, but this isn't always possible, and I'm not that strict about it. For breakfast, especially, I find if I eat I actually come down much faster than if I don't eat.
Until recently, I considered anything under 180 to be pretty fine. My control has recently improved a lot, so now any time I am over about 8-9 (150-160) I'll go, "Hmmm, that's not normal, what happened there." There are some that have much stricter guidelines than this. It all depends on how consistent your BGs are (and some people have more swings than others, for various reasons). Someone who is just getting their diabetes under control will have very different guidelines than someone who is aiming for non-diabetic blood sugars.
Targets are also a good topic for your endocrinologist. I switched doctors last year and have not asked my new one what his suggested targets are, which I plan on bringing up at my next appointment in November. Of course, this will also depend on whether you trust and agree with your endocrinologist, as some fine their endocrinologist recommendations unsatisfactory and just come up with their own that works for them.
