I've read the section about Astral Space in the core rulebook and I'm not entirely sure I understand what it is the players see every time they open their perceptions to it. So here are a few questions to help me understand it better:

Do characters who are perceiving astrally but trying to interact with the real world suffer from penalties for partial/minimal light (in addition to their normal +2 modifiers)? Would they be able to see people's auras in complete darkness or a cloud of smoke from a smoke grenade?

In general, should I picture Astral Space as basically looking like Physical Space (The "Real World") but glowing in places with emotional energy and mana? How hard is it to find stuff that's been hidden really well in Physical Space?

I apologize in advance for the bombardment of questions but Shadowrun has an incredibly different Magic system from all other RPGs I've played before and some of these concepts are brand spanking new and unfamiliar to me, thus I'm doing my best to understand them.

Light and penalties from lack of it has no effect on the astral, but obstruction modifiers apply. They are not subject to total darkness, but can be hindered by smoke grenades. In general, the physically visible is a faded, greyish version of what they see with normal eyes. All living things glow astrally, but considering how much ambient life there is in most locations (and the glow that seems to eminate from the earth itself), it doesn't stand out.

Hidden things are usually just as hidden, unless you carefully set it so that astral vision will have a clear view (only really possible with living things or active foci/spells).