First thing, I had to dig trough the thread to find this:
http://wiki.volvo300mania.com/index.php/Main_Page
That is certainly logical place for wiki as it is in same url thing as rest of the site, but I'm still unsure after reading all this that if this is which you are going to work with?
Admin or OP could edit first post to reflect location of wiki and current status.
Second thing.
I'm one of the admins of rFactor2 wiki, which is still under construction, we have talked from it with great length with other admins, about style etc.
One of the best wiki I have seen is this
http://www.modwiki.net/wiki/Main_Page How things are laid out, categorized etc is really good in there, first you pick what is your area of interest (could be engine, drivetrain, suspension etc) then you pick what are in there (maybe something like 340 1.4 ?) Modding and such could be also there next to car models or it could be whole main category.
One have to think like if you would be searching information to solve some issue on your car as that is how most likely users are coming to wiki, there is something they want, that something has main category where it belongs and some sub area in that category.
Worse thing to do is just throw stuff in there without planning.
Searching is often used to access information, but also some menusystem like in modwiki is really great when one is browsing for information.
Third thing.
Yes, I have hosted some stuff, but then again I have 50GB storage with unlimited bandwith (200GB/month has not been an issue yet), so there is no problem for me to host stuff, it is only a 5 toymoney in a month and it is my photo hosting and other file hosting at the same time too.
Important thing.
There is potential problem and security risk when one uses chmod 777, that should not be needed if users and groups are set properly, especially bad it is with directories, but even with pics you give then any low level hacker keys to remove/replace them and as nowdays even jpg contains viruses, he could replace images with those containing viruses, making whole lot of problem and issues. 664 or 644 are ones that should do the work.
777 itself is not very dangerous, but you can think it being one door of many and if first door is busted and second door is open, there is nothing standing in evildoer's way.
Anyway that might give some food for some thoughts.
Edit: You can use help of Wikipedia to format articles properly
http://en.wikipedia.org/wiki/Wikipedia:Guide_to_layout at least I need a lot of that page to be able to get matching style, when I start making pages for rf2 wiki, it is still bit of starting phase, though.