How bad is it really though? A crack near the garage edge is pretty normal for asphalt and it's gonna move with the seasons no matter what you shove in there. I've watched my neighbor fight the same battle for years, refill it every spring, and the crack still comes back every winter. The honest truth is filler is more of a cover up than a real fix, so even if you did it perfect it might open back up. That said, if you want it to stay longer, clean the crack out with a wire brush and a hose, let it dry good, then use the pourable stuff and fill it slow so it goes all the way down instead of just skinning over the top.

Does your panel actually support the resistor at the can, or are you just getting lucky with the loop length? I ran into the same thing at a school district here, and half the panels would show normal right up until the tamper switch opened. What I found was the resistor at the can only works if there is no other device between the can and the panel that can short the loop. Once you get a bad device or a chewed wire past the can, the panel reads it the same as a normal alarm and you have no way to tell the two apart. Saved me a ton of time on installs but it bit me hard on one building with a lot of moisture in the conduit.