I would like to make an AI CHaracter. But, I am having difficulty with pro's and con's for it. I want to base it around either the Pocket Hacker Agent (Unwired, pg 127) or an E-ghost in a commlink. Also I would like to know how do you get around some security measures (Signal negating paint etc.). I don't want to stick it in a humanoid drone it seems like it would go against the core idea of it to me. Any help would be greatly appriciated. Thanks to all.

pro: basically, you can get everywhere if you can throw a drone there and point a signal in the general direction . .
con: if someone pushes a wrong button and formats the space you occupy, that is about the most embarassing character death i can imagine . .
as for the appearance: just use some sort of itty bitty little small hover/skimmer or zeppelin drone with an holo-projector to show an image you want to be know as your face to the rest of the world O.o

is an AI immune to magic?
if the mage casts at the hardware the drone is occupying right now, that's something different . . but can you cast MIND PROBE at an AI for example?
Is there a Slay AI spell?

Pros: Quite a good chance for roleplaying. You are the matrix and you can push up the matrix attributes of somebodys device with just making your home in that device. You have no body, so you can't be killed for real, unless they destroy your homenode while you occupy it. Magic doesn't affect you in any way and if it does it's just indirect like the spell that shoots the drone you rigged. Your home is your castle, no one can do anything there unless you want it. A homenode is like a permanent admin account. And if you want to show a face, use "FaceGen 3.0" from Ares who needs holographics in the age of the matrix?

Cons: If you don't go drone commander, physical warfare can be quite boring for you, except your opponents make heavy use of meshed networking and you are a skilled infiltrator. You are quite slow without many chances to speed up your three ini-turns.

I'll see your questions and raise you another: how do you get LOS on an AI?

I think your question answers the previous questions.
Since it is impossible to get an LOS on the AI itself, it cannot be affected by magic. It's the same as how a mage cannot use magic to protect against a hacker's exploit program being used against their commlink. They have no LOS to the program, so nothing they do can affect it.

AIs do, however, have a physical location, that being the node they are occupying. This will be vulnerable to magic, but only to magic that affects the physical node, not the data inside.

If an AI having immunity to mind probe seems unfair, consider that they are almost certainly vulnerable to various digital methods of probing their memories, more so than living beings. AI's won't interact much with mages, but hackers and technos can pull all sorts of nasty stuff on them.

The main pros of being an AI are actually in their resilience. Killing an AI is pretty damn hard. Not impossible mind you, and it's certainly not unreasonable that after the first time it reforms, and the security forces gun it down again, that they'd decide to reboot the node. Even if they didn't specifically know this would kill the AI, it's still a reasonable response to "huge fraggin hunk o' code in my system that just won't die!"

The cons are all about what you can't interact with. Basically playing an AI is a fairly specialised role. Depending on how you choose to play it, you may well spend a lot of time just watching and commenting from the sidelines. If that floats your boat, go ahead and stat one. Otherwise, look seriously at using drones and stuff.
If you really want to do pocket hacker, just ride around in a team-mates commlink on the runs. That'll get you past wireless inhibiting paint, no problem. As soon as you're inside the building, jump into the main node and start wreaking havoc with the security systems. An AI's job is basically to take complete control of the enemy security setup and turn it to the runner's advantage.

Hmm... that gives me another idea: AI Spider. Cool piece of oddball security for a run. Would scare the Hacker something fierce, especially with the Home Node rules. Ouch.

The guy who runs an AI PC in my game (drone commander type) got round wifi-inhibiting paint by using a Bust-A-Move with a miniwelder to cut through walls/doors/windows and a micro-tapper bug drone to drag a fibre-optic cable with a wireless adapter at either end through it, creating a bridge.

Of course, when the Bust-A-Move was spotted by the TI system on the high-security property they were infiltrating last run, his entire entry strategy was destroyed in a hail of anti-vehicle minigun fire, but what can you do?

=i)

Blow a huge fragging hole in the wall with high explosives?

if the AI makes the built in comlink of someone their home node and the person that just happens to live around the comlink dies . . what happens to the AI?

Nothing until the link is ripped out and wiped to prep it to be implanted into some other slot.

and the AI can always move out, if it can flee onto the matrix.