Sounds like you probably need to install a new hard drive in it, as those problems point to a failing hard drive. Installing a new HDD on these TiBooks isn't terribly difficult, there's an iFixit guide for it, but it essentially only involves removing the battery and bottom of the laptop to get to it.
If you're replacing the HDD, I'd recommend getting a DeLock IDE 44 pin to mSATA adapter that looks like the one below. Other brands sell these, but make sure it uses the same Marvell chipset. That along with an mSATA SSD of decent brand and size (I'd recommend 32GB or more), should get you a nice, speedy, PowerBook. SSD Quality is crucial here as the PowerBook offers no TRIM or other garbage collection, so the SSD needs to be able to do this itself. Cheap Chinese SSDs likely don't do this and degrade over time.
