Questions on VFR sectionals and TACs

There are some mysteries that I've encountered while learning to read
VFR charts:

1. I see airports with dashed cyan circles around them that I presume
indicate Class D airspace (based on the chart legend). However, the
circles are not always the same size, and I don't see any indication
of their radii; how do I determine how far out the Class D circle
extends (short of measuring it by hand)? Also, is there a convention
for the center of the Class D circle (tower, or whatever?)? They
don't seem to be centered on anything easily identifiable.

2. The legend doesn't appear to explain lines that consist of a solid
cyan line with cyan dots inside. It seems to outline things like
wildlife refuges or parks and stuff like that. Is this just an extra
line style used for things that don't otherwise have line styles
assigned, or what? Are there any restrictions or other things to know
about spaces enclosed by these lines, or are they for information
only?

3. I'm confused about Class E airspace. If I understand correctly,
the absence of any other indication on the chart means that Class E
starts at 1200' AGL, and extends to 18,000' MSL. If the shaded purple
border encloses an area, it's Class E starting at 700' AGL and still
extending to 18,000' MSL. If it's a shaded cyan border, it means ...
Class E starts at 1200' AGL and extends to 18,000' MSL?? (The chart
says "abuts Class G," but I'm not sure what they mean.)

4. The cyan chain-link Class E border confuses me. Which side is
inside the Class E? The altitude is the floor of the Class E and it
still extends to 18,000' MSL, right? If there are different altitudes
on each side of the chain link, what does that mean, and where do I
look for the other border of the airspace? For example, just west of
Buckeye on the Phoenix sectional, there are chain links and stuff all
over the place, and I'm having trouble figuring out what the floors
are and where. Around Western Sky airport (W 113° 40' N 33° 46'
roughly), I see the shaded cyan border for Class E at 1200' AGL, but
in that area I see 7000 MSL, and a chain link on the right and bottom.
There are chain links next to airways, too. I don't know which
altitude applies where.

Can anyone explain the above to me?

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