First off, a lot of the hacking rules are still a little up in the air as to what to apply and when, so if you're not sure about something, it may not be because you missed the explanation. And following on from that, the replies you'll get to these questions will vary slightly according to each GM's interpretation.

That out of the way, I would answer them as follows:

1. In RAW, the active alert firewall bonus of +4 only applies to the intruder that triggered the alert. So you can't pre-emptively go on alert against people. They have to botch their hacking job first. The other aspect to alert is more a case of behaviour, i.e. the node will be sending messages to corp hackers, activating IC programs. You can do that yourself on your own nodes regardless of "alert status." Just tell your IC / Agent to stay active. The only downside is the usual effect of running that program on your comm which is, as you say, a performance hit.

2. Unless you're talking to someone through some weird old fashioned phone thing which you wont be, then yes, in my opinion. This might be more open to debate than the last point, though. The signal is like any other data stream coming through your comm link and you can locate the origin using Trace in the normal manner. I'd want a Matrix Perception test first. If you had the access ID instead, then again I'd allow it, but I would have most people you want to trace (Johnsons, fixers, etc.) using a spoofed access id. Again, IMO, once the spoof is done and the connection broken, you can't unspoof it and find where it really came from.

An access ID is like a MAC address as one way to alter it other than spoofing is with a Hardware + Logic roll to physically alter your commlink. They're definitely meant to be static, not dynamically assigned when you connect, etc. (As an aside, it's not widely known for some reason, but it actually is possible to alter a MAC address).

Hope this helps. The next reply might disagree with me, though.

-K.

No.

Yes. Absolutely. You could do everything you normally could with an icon on a local node. As far as I know, you can even Attack them.

Not really. You're best bet would be to do a Data Search in the com directories and see if they have a listed address.

Mmm. No. Again, unless the Access ID was listed.
It's generally much easier to get an Access ID than to track someone. If the rules worked this way, there would be no reason to track anyone ever. Access ID tells you who did it, but not where they are. Although difficult Data Seatches and the like might be able to tell you where that person lives or works if they have a SIN.

I always treated it more like an IP address. But I think the rules support your interpretation better since it is possible to change the hardwired the Access ID. I suppose its both.