Acquire vs AcquireFast

What are the differences between acquire and acquirefast?
What are the advantages to acquirefast?
Can the twain capabilities in the acquirefast call be overridden using a template file, LoadTemplateFile.

mesa,

One difference between Acquire and AcquireFast is that the latter saves the acquired image from the scan directly.
The main difference, though, is that AcquireFast can achieve optimized performance with high-volume high-speed scanners if it is used in conjunction with other Fast Twain features of LEADTOOLS.
This can only be used if you own a Document Imaging or Medical Imaging toolkit. For details, see topics related to Fast Twain in our help files for you programming interface (C DLL, .NET, etc.) such as "Get a Fast Twain Scan from a Scanner".

This answers your first and second question. For the third question, if you mean setting the capabilities using a template file and then acquire an image using AcquireFast, then yes, that can be done as long as these capabilities are supported by the scanner. However, if you perform the optimization steps first, you might want to save that template to use it later and not load some other template that changes the optimized settings.