First, a question: the CV boot (CV shaft) is also the axle boot, right?

Anyway, the boots that fit the axle and the wheels seem to be worn on my Civic. After extensive research and reading (here and elsewhere), I figure that I need to replace them but not the axle (?). One boot on the driver's side is cracked or ripped. I just replaced both boots and the axle is from a junkyard last winter. It didn't last long?!? The car creaks at the site (?) sometimes when I turn or turn the wheels. Grease can be seen coming down from the boot and end of the axle shaft. I'm still driving the car but I know I need to replace the boot at least. If I did the replacement tomorrow or during the week, is it still possible the axle will still be usuable? I am not sure at what point, the axle needs to be replaced. Is there some visual check that confirms whether or not you can keep using it? Other than it being broken or what not. I know I want to avoid the point when the car collapses from a broken axle or slips out entirely.

Or should I lean on the safe side and get another axle from a junkyard? I probably need to replace both boots but a visual check on the drivers' side shows a fairly large rip in the boot.

If I'm not mistaken, I read here that you really can't do any preventative maintenance to avoid the boot ripping except, perhaps, grease the area after installation. With Honda axles and CV axle boots, you don't need to insert extra grease, right?

Thanks for all replies.