How bad are the cracks? Bondo is nice because it dries so quickly but you can use some actual concrete mix and it may last longer and adhere to the existing concrete better. Cement-All works pretty well (https://www.homedepot.com/p/Rapid-Set-55-lb-Cement-All-Multi-Purpose-Construction-Material-02010055/202188447) or if you're at Lowe's they carry "Pro-Mix" by Sakrete.
They're just normal expansion joints between 8-10 foot segments of curb. Nothing you couldn't grind over, but it will slow you right down and feel like trash. I'm not overly worried about how long it lasts, since I'm not 100 percent sure if I'll be left alone skating there, although I have high hopes. But that rapid set patching mix doesn't seem to take too much longer to be able to work with and it would obviously last a better, so maybe it's worth the effort of doing two nights of prep.
Its not the most durable in the world, but it works pretty dang well until it fails. There after, just repatch as needed.
I'm a fan of smoothing out the cracks, if'n you're putting in the work already, don'tcha know?
Yeah, I want a curb where I can (hopefully) do my thing in peace in the evenings and just be able to have fun with it, so I would definitely prefer it to be as nice as can be. This one's double sided, which is sick, but it's just got hard, rocky dirt on the other side from the pavement, and it doesn't seem fun to slam on that. Maybe it can be a test run, and hopefully I'll find my grail curb before too much longer.