Texas Mac Man is correct, there is no reason to do any zeroing, or multipas random writes. Unless you are selling on your mac and want to make sure data is unrecoverable.
On very old HDDs there used to be a technical advantage in doing this, because older HDDs (i'm talking 486, 20MiB capacity old) were much less reliable, they were not as megnetically stable, and bad sectors were common without any physical platter dammage. Zeroing when formating the drive gave a better baseline magnetic polarity to start with, (the magnetic polarity of a bit on a platter is not completely hard, it has an analoge nature in that it has degrees of polarity) provided this is well ether side of the threashold that determins if it is a 0 or 1 there are no problems. I guess old platter material had a higher magnetic permiability and thus lower retention of polarity making it creep closer to that threashold.
This is why if you truly want to destroy data on your hard drive you have to do even more than one pass of zeros, because beyond a simple block read, you can actually ask the disc controller on modern drives for more detailed information on the specific degree of polarity of a bit... if you imagine zeroing a section of disc that contained a perfectly intact file, then you can read back the degrees of those zeros and simply scale them up (i.e move the threshold), also if the file was overwritten with some other data then you could subtract those values from the variations in polarity to recover the original data underneath.
All of this is really extreme of course... for the average person, zeroing is going to be enough to disuiade them from trying anything further than a data recovery app, because it's increadably time consuming and requires more specialist software.
anyway, the point is on a modern HDD zeroing makes no difference for performance or reliability. what makes way more of a difference for reliability on HDDs is operating temperature and shock... shock can mess with the actuator and at worst crash into the platters, and high operating temperatures make the bearing wear out faster.
If you are really worried about sensetive data, i.e. it's work related etc, then simply never pass on the physical HDDs, keep them or destroy them in a cheap microwave over. or alternatively use SSDs which for the most part are practically impossible to retrive contiguous (meaningfull) data from.
For the 7 pass erase the progress bar will just appear to go slower... i don't know weather or not the actual process does each block individually 7 times in a row or the entire drive 7 times in a row, but making the progress bar indicate the entire progress is trivial, and it would be absurd to code it differently.
Disabling java is a good idea, most of the vulnerabilities on OS X (this one and previous ones) have been via java, the majority of apps do not use java, and the majority of websites do not use it ether. in fact the only non java vulnerability on OS X that wasn't patched before it was announced was the DNS vulnerability but that only really applied to people running DNS servers not those using public DNS servers.
I would consider chrome again... the slowness you are experiencing may have nothing to do with safari specifically, unfortunately http just IS slow, and if you access websites that use lots of discrete http resources then things can get VERY slow.
no browser is perfect, but you will find a lot of developers recommend chrome, it's a good browser, good for the user and it also pushes web standards (which includes security).
Firefox used to be a bit of a star for eating away the market share of IE, and many people (myself included) are grateful for that, and while it has reasonably good compliance in terms of basic DOM stuff (which IE was crap at for years), it's not as good as people used to think for security and reliability. One massive problem is memory leaks, in this respect it's just as bad as IE.