As for the dizziness, did you get your blood pressure checked? Are you sure you weren't experiencing some dysreflexia?
As for UTI prevention, I think it's a given that it's damned near impossible to truly self cath in a clean way. I had one urologist put me on a prophylactic dose of antibiotics. That always worried me, because of all the risks associated with long-term antibiotic use. I've since switched to a new urologist and she's having me irrigate my bladder with a solution of gentamicin, which avoids the issues of long-term antibiotic usage. And, so far it's been working great. Mind you, before the antibiotics I averaged a UTI every month and half or so.
Here's a couple links to info about the Gentamicin.