I would remove everything in your quote. It's just some search engines installed by adware/toolbars and some Chrome addons that you can always install again if you find out you need them (but it'd be best to find an alternative). Won't make a difference on your HDD space but might lower your CPU/RAM usage a little (and who knows what those Chrome addons are doing in the background?)
It won't break anything, it might lead to low memory errors and crashes if you run out of memory but that won't happen unless you run several ram-heavy programs at the same time.
Depends on how much memory you have though. On my laptop I have 16 GB RAM, and I disabled the pagefile completely. The pagefile should never be used much anyway because it slows down the PC a lot when in use, so making it smaller will often help. Windows tends to make the pagefile far too big. If you have 8GB you can safely set the pagefile to half that. If you have less, set it to the same size as your RAM.
It doesn't sound like your issue is related to those though. To me it sounds like you should run Disk Cleanup and CCleaner. Tick all the boxes except things you really want to keep, google ones you are unsure about. I'm surprised there weren't more files in temp but there are other locations that can be cleaned.
Also, grab WinDirStat
http://sourceforge.net/projects/windirstat/
It's a great graphical tool that I use to see what's eating up my disk space whenever I'm running out and I'm not sure what to delete. Each folder is shown as a cluster with files in that folder and its subfolders represented as rectangles of the same color, and by looking at the size of the rectangles or individual clusters you can easily spot the main culprits, there's also a file/folder list that's sorted by size. I like to use the graphical view for spotting huge folders that I can just delete, and the list view for deleting individual smaller files or subfolders.
