How do i convert TIFF files to JPEG's in photoshop without losing the image size or resolution?

You can't. Tiff files are non compressed files while Jpegs are compressed. The best you can do is to save the Jpeg files as the highest quality with the least compression. This will turn a 40mb tiff file into about a 5 or 6mb jpeg. Converting to Jpeg doesn't actually change the physical size of the picture. It would still be xxxx pixels by 0000 pixels. It just compresses the data and reduces the file size.