I use CCLeaner multiple times/day on multiple computers to delete everything it can in all of my temp folders. I have never run into any situation where it deleted anything that caused a problem and I've used it for many years. There are a few files stored there that are used by my Avast a/v program and they can't be deleted by CCleaner because it doesn't have permission by default but they are very small and get updated regularly because they are always active. Even if you tried to manually delete those active files you couldn't anyway.

Browser cache, cookies, bookmarks are not stored in temp folders but in specific folders created by the browsers themselves. They can optionally be deleted manually or using CCleaner but unless you have browser cache set to extraordinarily large size they don't usually take up much space. Cookies and bookmarks take up little space in their own non-temp folders. I have my browsers all set up to delete cache when I close them.

There is a setting in CCLeaner to only delete items older than one day to be extra careful but I've never used that.

I use my SSD for my operating system installation and all of it's default files and folders and that is the fastest way to utilize all it's speed benefits. I store media on a separate hard drive so the max size of my whole running Windows 7 installation is never more than around 40Gigs including swap file (with 4 gigs of RAM).