The question of stealth, (some GMing questions I'd like my players not to read). Options

[Fatum]

And yes, I am looking at you, you know who you are.


The following questions might seem obvious, but my group has run into trouble handling them, so I'd like some advice from GMs more experienced.
So, there are characters who are into sneaking: stealing things, setting explosives, whatever. That requires some infiltration and some teamwork on their side, and as long as only tech security with some human backup is involved, everything works fine.
Now, as soon as we throw the mages into the equation, everything gets a bit more complicated.

First, is there a way to fool detection spells like Detect Life? With the amount of detail it gives, everything a wagemage has to do is have it sustained at Extended range, and be aware of anyone entering the compound?

Second, how do you deal with spirits stealthily? With Watchers, you could at least try fooling them - say, with the team's mage placing a wall before them (but that still raises questions like "wouldn't it try to go around the wall" and "if I cover it with a dome-shaped barrier, won't the wagemage lose his connection to the watcher and feel that?"). But what about the full-fledged spirits?

Also in what comes to mages, rules state that a mage can cast as far as he can see - but a metahuman can see as far as several dozen kilometers, especially with cybereyes!

Third, sure SR4 makes hacking more streamlined, but is there a way to deal with tech security without a hacker on call and without telling everyone that you've been there? Do you just let your infiltrators roll Infiltration against the cams/guards monitoring the cams, whatever the circumstances, even with a shadowrunning traversing a typical empty office corridor under the electronic eyes?
Also, each hack means a chance to warn the security you're there - how do you handle failures when hacking on the fly?