Limit search to specified Folders or File Types in Visual Studio?

Yes, in the find/replace window you can:

• specify the file types in the "Look at these file types" option
• and choose the folders in the ... button of the "Look in" option.

Fastest folder search in VS:

As said in other answers, there is no immediate way to limit your search to a given folder within the current solution. (There are at least 3 feature requests for this in visualstudio.uservoice.com that have all been closed for lack of upvotes.)

But here is the fastest workaround that I could find.
Works without leaving VS and with keystrokes only (no mouse action required):

• In Solution Explorer select the folder to search within.
• Press Ctrl-C (copies folder path to clipboard).
• Press Ctrl-Shift-F to open "Find in Files".
• Enter your search term, then press Tab to forward the cursor to the "Look in" field.
• Press Ctrl-V to paste in the folder path from clipboard.

2020-Update: Actually you can select the folder (also the current directory with two clicks) and define file types in Microsoft Visual Studio Professional 2019, Version 16.7.5