1) when you go full matrix defense, it says add your firewall. but when reading "attack" matrix actions - like data spike (Cracking + logic vs. Data processing + firewall) or Tarpit (same as data spike). do you add firewall twice? eg. Data Processing + firewall + firewall?
Yes.
If you are attacked by Data Spike or Tarpit while using Full Matrix Defense you would oppose it with Data Processing + Firewall + Firewall rather than just Data Processing + Firewall.
Note that the action doesn't seem to work against any other matrix action than the two you listed (technically it doesn't even seem to work against Brute Force attempts).
2) I've read elsewhere that a decker can slave other players gear behind your PAN, and kind-of act as a Matrix shield to your team. I can't find that in the rules, am I missing this section and how that works, or is this edition blindness?
The original author did not intend the small limit on devices that eventually got decided upon and also went into final printing. To get back to the original intent a suggestion was that you could daisy-chain multiple commlinks. This is not supported by the rules as they are written but at the same time it is also not strictly prohibited by the rules as they are written
(but strictly following the general rule structure we had in all editions of Shadowrun it would not be rules legal to do it since there are no rules that specifically allow you to do it).
As the rules are written in SR6 you can only include Data Processing Devices behind a Commlink (or Cyberjack). And Device Rating x 3 Drones behind a Rigger Command Console. Period.
3) is there any way that I can prevent a decker from entering the Matrix - either in VR or AR? I am assuming the use of a Jammer or jam signal. noise only indicates a penalty once in the matrix, but not mention of stopping someone from entering? is this possible, or done some other way - eg, having to hack into the decker's cyberdeck? just don't know.
There are a few edge cases. Put the hacker inside a Faraday's cage. Brick or physically destroy the device he use for accessing the matrix. Format the device he use to access the matrix and then have it reboot. Situational noise (spam zones, use of directional or area jammer, static zone etc). Obstructive noise (diving in salt water, jam signals matrix action, heavy use of wireless negating paint etc). Being without a satellite link in such a remote location that you don't have access to the matrix unless you have a satellite link. There are probably a few more.
But by default everyone are always connected to the matrix at all times.
Hackers often also have access to software that help out reducing noise and there is also a 2-edge action that let you ignore all noise for the duration of one matrix action.
Beyond that, Riggers also have a lot of built-in noise reduction.
4) total newb question. I assume that all PC's, due to everyone having their own commlink, can enter the matrix in full VR (ASIST module), and travel around similar to the decker. Is it typical for all party members to travel together, or the decker enters the matrix alone?
You don't need to be in full VR in order to "travel" around the matrix. You can also open up a "window" in AR and have your matrix perception "travel" around the matrix. You can also enter hosts while still in AR mode. Basically the only thing you cannot do directly from AR is to jump into a vehicle or drone.
Typically it is mostly only the hacker that is traveling around the matrix, but anyone with a simple commlink can for example join a matrix meeting and if you also have a few points in the electronics skill then you can also use the matrix as a platform to do legwork.
For VR you need a direct neural interface and you need a sim module. For hot-sim VR you need a sim-module that is modded for hot-sim. Technomancers can access both cold-sim VR and hot-sim VR without devices.
You get DNI by wearing trodes or implant a commlink, datajack, cyberjack or control rig. Technomancers can get DNI to a device by having the Skin Link echo and physically touching the device.
Cyberdecks come default with a hot-sim module (which enable both cold-sim and hot-sim VR). Internal commlink and the Control Rig implant both come default with a cold-sim module. External commlink commonly have a cold-sim module. Sim modules can also be upgraded to hot-sim. Cost, Availability and Legality for both sim modules and hot-sim upgrades can be found in the 2019 Aug errata.
