Ok. I understand the basics of how this all works. In order to access a device or a program, you need to have it subscribed to your comlink. However, I am not so sure on what exactly needs to be subscribed to work, and what does not.

For example:

Sally Samurai has a rating 3 comlink. She also has a smartlinked Ares Alpha, a cyberarm, wired reflexes, ear buds, smart glasses, AR gloves, a biomonitor, and her motorbike.

Which of these devices needs to be subscribed? Do 'peripherals' like ear buds require a subscription? Does cyberware?
I have played SR4 before many a time, but am running for the first time soon and am trying to be perfectly clear.

SR4A p. 224-225 has the ful details, but in short, any device you want to be able to immediately access through the matrix, needs to be subscribed. I'd say that most of the time, you will want the cyber, earbuds, glasses, and gloves subscribed. The Alpha and motorbike can be sometimes subscribed, and the biomonitor occassionally based on usage.

unwired p54, data requests may be of interest.

Huh. I guess it just seems somewhat strange and highly unnecessary, to me, to require basic IO devices to be so, in modern parlance, 'processor heavy'. I mean, basically you are devoting a significant portion of your computing power to running your keyboard and mouse.

The other option instead of glasses, gloves, and earbuds is to add a sim module and run the commlink through DNI (either implant, trodes, or datajack). This option would either eliminate the subscriptions for "keyboard and mouse," or cut the items down to a single subscription (the trodes or 'jack).

Maybe I've been totally misreading the intention of subscriptions, but the way the rules read to me... why on earth would you be subscribing to stuff that's in your PAN. That just seems silly. Subscribing is logging into a node with your persona, over the matrix. Whereas your PAN is more or less, a single node within the matrix. As I see it, anyways.

So, I've always had it set up so that instead of each PAN device being a separate node, someone would have to hack your personal node/commlink and then from there issue commands to the respective devices... just like controlling security cameras from a building's network.

Again... I could be totally misreading this, but in SR4A p.224 it talks about a commlink projecting a node, with icons for everything in your PAN. Sooooo... why would you need to subscribe. It's all just... there.

Unfortunately, Slaving needs Subscriptions.

Most people tend to completely ignore the rules for subscriptions, though.

Just for clarification, cyberware does not need to be subscribed unless you want access to some features that would require you to connect the cyberware to a PAN, like repair/diagnostics or devices that you have shoved into a cyberlimb (for example, you have a Radar unit in there but you don't have an Image Link to view it through internal cyberware). Most of the crunchy bits for this in the rules can be found on p31-32 of Augmentation ("DNI and Wireless Functionality" and "Cyberware Triggers"). Specifically:
"Unless otherwise stated, cyberware that is capable of being activated or deactivated can be done so with a mental impulse. This is because the cyberware has been connected to the user’s nervous system, so it can be used in the same way the user would move a finger or flex a muscle. Typically, when a cyberware device is installed, the user must spend some time adjusting to this new ability and will doubtlessly trigger the device accidentally a few times. Activating or deactivating cyberware is a Free Action."

If you run out of subscriptions, it's fairly trivial to get another Commlink and run it as a Slave node wired to your primary Commlink as a "router" device. This is legal because of Unwired p59 (PAN Connections and Protocols):
"Note that each device does not need to be connected to every other device in the network, as long as there is a chain of connections leading to other devices (i.e., the PAN is also a mesh network)."

Also, it is perfectly legitimate (although much less secure) to run all of your peripherals as separate sub-nodes that are not slaved. This allows you to save on the cost of subscriptions. As long as you have one subscription free, you can access a sub-node on an Ad-Hoc basis, when you need it on demand. However, if someone hacks your sub-nodes that aren't slaved, they will have an easier time doing it. Not so bad with AR gloves (What are they going to do? Make your hands itchy?), but potentially bad with your guns, earbuds, smart glasses, etc.

Giving the cyberware the enhanced hacking protection of being slaved to your high Firewall rating commlink that's got IC analyzing every inbound connection is a pretty handy feature.

For people who don't just turn the wireless off on their implants, anyway.

You can also cluster a group of devices and subscribe to it as though it is one device. I don't recall a section that states clusted devices loos their basic functionality, just share processing power and networking.