I haven't had any trouble at all with creating PDF files from 9.5 in OSX. In fact I just created one to verify that there weren't any problems going to an Arch D size. There are two ways to create a PDF file directly.
But first, let's talk about sheet size. We have an HP 1055cm large format printer. This printer has a PPD file which describes page sizes up to Arch E. If you don't have a large format postscript printer just follow this procedure. First, download the drivers for this printer from hp's site or versiontracker (search for "HP") Or here is the link for the lazy: http://www.versiontracker.com/redir.fcgi/kind=1&db=mac&id=11199/ install the software so you get the PPDs. (PPD stands for postscript printer definition, BTW, and describes things like available page sizes, etc. The actual files are just text can be opened with TextEdit and edited; however, this is generally not advised)
Now, go to Print Center and create a new LPR printer ("Add Printer"). This will be a dummy printer. Put a bogus local ip address in -- like 192.168.0.5 and under the "printer model" pull it down and select the 1055cm PPD. If it isn't listed in the pulldown menu just select "other" and go an find it on your hard drive. You can also fake it out with the old OS 9 version. Anyway, create the printer.
Go to page setup in VW9.5 and tell it to use this bogus printer. Under Format For... select your bogus printer and then all your available oversize sheets will be available. Voila.
As far as actually creating the PDF file there are a few options. The option I have found most useful has been to click the "preview" button in the print dialog. This opens the Preview app with your sheet displayed. From there you can "Save as PDF" (or TIFF) from the file menu. There are two other ways. You can, of course, click on save as PDF in the "Output Options" tab of the print dialog. This isn't necessarily as reliable as the last method. The last option is to save the print job as raw postscript. This .ps file can then be ripped into a PDf file by MacGhostView or PStill (look on www.versiontracker.com) on OSX or brought in to Classic and ripped via the still-not-carbonized Acrobat Distiller. You can use Acrobat 5.0.5 Carbon (full version, not reader) to bind up multiple sheets.
Your mileage will vary with MacGhostView and PStill. You should also watch your fonts as I have found that fonts do not always get properly embedded. We use Tekton (postscript) and that has worked okay. For maximum portability use a font that you know the person or service bureau on the receiving end has a copy of.
As far as lines being wacky, etc. I don't know what to say except that we haven't had that kind of problem. Try to make the PDF file with a few of the various methods and see if your results vary. BTW, this is assuming you have all of your OSX system software up-to-date.
Hope this helps