Here's how I do it, and because I do it this way I wonder if Lightroom would be worth buying because this feature is what everyone raves about Lightroom for.
When in Bridge you can select multiple files using several different methods. CTRL+Click, Shift+Click, or you can even go into the review mode (CTRL+b) and then push the down arrow on any that you want deselected, and it will leave the rest selected. Once those files are selected, just double click (or if you've done tricky selections right click and say "Open in Camera RAW" since I usually mess up my double clicks if I've spent time selecting). Then ACR will open with all of the files, which can be a little slow to start, but usually isn't too bad. You will have thumbnails of all of your selected files available to you on the left side of ACR, and from there you can edit the open picture, or select multiple files and it will apply all of your editing to all of the files, or my favorite way is to edit one file, and then select the other files that I want edited the same way (again, using Shift+Click or CTRL+Click on the files on the left) and click the Synchronize button that is at the top of the list. It will synchronize the edits to the picture that you initially selected.
Lately, I've been doing the synchronization in Bridge, and use it to help me cull my pictures so that I can only spend time editing the good ones. I will edit one of the pictures with my general ACR edits, and then in Bridge, copy the develop settings (CTRL+ALT+C or Right Click>Develop Settings>Copy Settings), and then paste them (CTRL+ALT+V or Right Click>Develop Settings>Paste Settings).
I learned a lot of this by watching Youtube videos and then experimenting and googling (I knew that there had to be a shortcut so that I wouldn't have to right click and scroll through my presets to copy the develop settings).
Oh, and you can get ACR presets, and apply them directly in Bridge via the develop settings.
If you want to apply actions do like Adrianka said, and it runs them through Photoshop (or you can run them through to save as JPG, etc.)
Bridge is REALLY powerful, and I feel like it's underappreciated because of Lightroom and I have had a hard time finding places to learn it.