@DrD,
It’ll depend upon what you want to do. Generally, in scenes, Disarm commands require a PIN to be stored and Arm commands don’t.
For me, I Arm the house using Keypad one-touch before I leave. I then use this as a “secure” means of determining whether I’m at home or not. My Vera has a set of scenes that execute when it detects (via the Plugin) the house transition to this Armed/Not-at-home state:
a) Turn off the [Nest] Thermostats, or set them to “Away” mode to save Power.
b) Turn off all of the lighting
c) Turn off the Hot water pump
d) Turn off the Sonos units, the TV (etc)
e) Completely power down the AV Gear (not even standby mode, completely “off” via a WebSwitch)
Something along the lines of the reverse happens when I Disarm the house, which I also do via a standard Keypad.
For a few yrs now (3-4?), I’ve also had scenes that put the Thermostats into “Away” mode when I open Windows (etc), to avoid heating/cooling the house… again mostly for power savings.
These were done using the original [wired] sensors that were around the house, windows & doors (etc).
More recently I’ve added extra sensors to the house for the sole purpose of automation. These include:
a) battery powered micro-sensors (DCT2) for inner doors, so lights come on
b) ceiling mounted motion sensors (DG467) to turn on walk-in-closet lights
c) weatherproof motion sensors (PMD85) to turn on exterior lighting, and notify me when folks are approaching
d) hallway motion sensors (PMD1P) to turn on inner lighting
e) Garage door contact sensors/PGM (2WPGM) to detect if the garage is open, and notify me
The total power savings are substantial, which is what makes it worthwhile to me. The additional automation, like having house lights come on at night when disarming, also makes it worthwhile as part of a broader set of security measures.
With each thing added to the system, you have to balance off convenience and security. Each person will have different tolerances there.
Moving forward, I will add a [bi-directionally authenticated] mechanism to detect our cars coming home, and to open the Garage door and disarm the house as the cars come up the drive. The tech to do this [securely] is starting to be commercially available at a reasonable price.
I also like to experiment with tech, since it’s what I do for work 
Now, you can always tie your secure system (Alarm Panel) to an insecure one (opening the Garage via traditional remote), it’s just something that I prefer not to do.
Technically, you can do that with the Panel itself, and no other components.
For example, you’d use a [Paradox] Keyfob in the car to disarm the house, and at the same time have it open the garage for you. I haven’t looked closely, but I believe you can do that, but you wouldn’t get the other benefits of the automation. It also means that someone that steals your car, or Keyfob remote left in the car, can get into your house un-noticed.
It would be more secure than using the regular Garage opener, since you’d use the Paradox Keyfob to “disarm” instead of using the regular garage remote (or a sensor on the garage door, which can be tricked with a strong magnet) but it still has it’s weaknesses.
Backup and Access…
I currently have an older Panel (a DGP-848), which I will upgrade to the EVO VHD when it comes out. At that time I’ll add an IP150 module, and have the iParadox app as a backup to this whole setup, since stuff does fail
)
My Vera is not attached, and does not backup, to any of the MiOS Servers. I have a home VPN for any internal access that I need (since it’s secure). This isn’t for everyone, since it requires a lot of configuration.