The wording of the section on Mana Barriers is talking about magical force to break through the barrier, not physical force. The comparison it makes to any other physical barrier is to inform you to use the same system for tracking damage to the barrier.
On page 315 in the entry you mention there is a chart which describes the caster's options for where the barrier will be present, and lists the specific page governing the spell or effect which causes the barrier. Mana Barrier itself can be found on page 294 of the 5th Edition core rules, and describes a barrier which does not prevent the passage of non-living (physical objects) or living things unless they are 'magically active.' For comparison, the next listed spell is Physical Barrier.
Unbound/uncontrolled spirits active in the area are affected by the barrier and have to contend with it like anyone else. Whether or not a summoning could take place on the other side of the barrier would very much depend on the situation and the barrier.
If a mage (or other affected being) desires to pass or have an item which is affected pass through the mana barrier they have three choices:
The subtle way is trying to magically bypass it as described on page
316, where every additional hit allows them to slip other affected
items or beings through with them. This is described as pressing
through the barrier, much like Dune's 'the slow knife will penetrate
the shield.' This approach does not automatically notify the creator of the barrier
The forceful way is to target the barrier with damage-causing
magics. This is handled 'just as you would with any other barrier,'
by dealing with its Armor and Structure ratings. These ratings are
equal to the Force of the mana barrier. The barrier must be overcome
in one Combat Turn or else its Structure refreshes. This approach
automatically notifies the creator of the barrier.
The third option (page 317, sidebar) is to attack the source or
basis of the barrier. In other words you can deal with the anchor,
destroy the lodge, or geek the mage responsible for sustaining the
barrier. With the source out of the way, the barrier is no longer a
problem. This approach, if it brings down the barrier, will notify
the creator automatically.
These choices are the same regardless of where the barrier is on the Astral Plane, on the Physical Plane, or on both.
Mundane gear and allies are unaffected by Mana Barriers.
Affected beings or items cannot normally pass through the barrier, unless they Press past it or bring it down. In some cases a mundane object may force them through the barrier (page 316) in which case they must pass an Opposed Test or be disrupted.
The effects of disruption are listed in the Astral Intersections passage on page 316. Foci are deactivated, spells end, spirits are dispelled, and living beings are Stunned. Afterward, foci can be reactivated, spells can be cast again, spirits can be summoned again, and living beings will recover from Stun... providing the owner of the mana barrier gives them the time to do all of this.
No amount of time is listed as a penalty for passing through a mana barrier, just the condition resulting from that intersection. Using the details of that imposed condition indicates a deactivated focus can be reactivated by the person it is bonded to as a Simple Action - if they are conscious. Likewise, spells and spirits can become available again in the time it takes to call them forth. Living Beings will recover from Stun normally.
Yes, you can.
Though shadowrun is surely a complex game system. It is by no means impossible to learn by yourself. The game is designed to cover three different aspects of the setting:
Mundane: These are the rules for mundane people, those who can neither cast spells, nor are willing to bend the matrix to their will. This covers a lot of the game rules actually, from combat to contacts and finding a job in the shadows.
The Astral: These are the rules for the mystical aspect of the setting, the other world, magic spells, spirits, rituals and characters who can channel their chi into their fists.
The Matrix: Here we have all the technological stuff happening, from security cameras, to the cybereye of the guards blocking your path. These rules are the realm of deckers and technomancers, and those characters should know those rules more than any of the other two.
This is also how the world is divided in the setting, we basically have three different worlds with different rules about how to interact with them. But each of these worlds are an important part of the setting on their own, with a lot of lore and mechanics involved.
The GM is expected to know all of this. But he doesn't necessarily have to memorize those rules. Whenever you decide to GM your first shadowrun adventure, try starting with one of the beginner adventures (or Missions). These are well-written adventures that will guide you through a normal shadowrun, convering all aspects of a regular adventure: finding the job, doing legwork, running the shadows, figuring out the plot twist, and finally, getting paid for it.
If you haven't already, take a look on the Quickstart Rules, these are ideal for convention play, as they are simplified rules and provide an example of play with a short adventure scenario so GM and players can get a feel of the system. The Splintered State is an introdutory adventure for 5th that deals mostly with corporations and the intrigue between them. While the Sprawl Wilds is a collection of convention adventures designed for short sessions (4 to 6 hours).
You can also delegate jobs to your players so they can help you out. If a player wants to be a hacker, ask him to make notes of the rules that are relevant to hacking things, infiltrate nodes, cybercombat and erasing his tracks. If one of the players is a mage, ask him to make notes of the summoning rules, how spirit services work, what each of his spells do and how to resist them, etc.
Of course, being such a rich setting, the more you read, the more you will know. So don't feel discouraged by the overwhelmingness of the game system, you don't have to use all the rules at once.
My personal experience with the setting is this: We played a couple of shadowrun games back in 2nd, but without any magic or mystical races, only humans. We had a hacker and other mundane characters and they ran through a few jobs i gave them.
Few years later, with a different group of people, i decided i wanted to play the 4th edition (the book is gorgeous), i read most of the core rulebook, asked my players to make some characters, we sat down and played the introductory adventure found on the Runner's Toolkit. It was a blast and an immediate success. Then we kept playing more and more, i kept reading the core book and bought the other hardcovers, and eventually we were all familiar with the rules.
5th edition came in, we migrated without issues and still play it now and then.