So, I just picked up the SR 5 book, and I'm a little confused, because the Matrix section isn't laid out quite as I would like it to be.

1.) Brute Force vs. Hack on the Fly: Aside from the different Dice Pools and Limits, (and the secondary effects), is there any reason why a hacker would choose one over the other?

2.) Are there different effects for failing the test (ie, the defender gets more hits)? This doesn't seem to be explicitly stated. If you fail a Brute Force Attempt, will it return harmful code and cause damage like a failed Data Spike? What happens on a failed Hack on the Fly test?

3.) Is there any type of safer, long-term extended test hacking like in SR4? Something that allows you to probe a target? Or is the idea that GOD would catch up to you before that happens?

Thanks

1) sleaze and attack actions have different negative effects attached to them, i'll discuss details in 2. also, you might have a bonus to one or the other (for example, you might have codeslinger for hack on the fly but not for brute force).

2) yes. you suffer damage on a failed brute force, just as always happens on any failed attack action (ie an action with a limit of your attack attribute). on a successful brute force, your target knows you succeeded as well, but won't necessarily see you (although they will almost certainly start trying to spot you). on a failed hack on the fly, they get to mark you (as happens with all sleaze actions), which also means that they can see you, regardless of your location, until you remove the mark and hide (you must remove the mark before attempting to hide). brute force is better in situations where you only need to get in for a little while and have a relatively low chance of success (they have no warning you're there until you succeed). hack on the fly is better when you are likely to succeed, but terrible if you're likely to fail (being marked is an absolutely awful situation to be in).

3) not really. unless you count non-hacking solutions, like persuading a sysadmin to legitimately give you a mark on their system. arguably, a technomancer may or may not be able to puppeteer someone into giving you a permanent mark that won't disappear on logoff, but there's no way to guarantee they won't notice and retract that mark. and even then, taking several points of fading is only arguably safer

The two tests may do the same thing, but they use different skills, different limits, and the defender rolls a different Attribute when resisting. Which one your decker favors might depend on the character's skills, specializations, and deck configuration.