The lpi is how close lines are placed on paper during printing. This is important when considering the output of your file. For black and white, there are only two bits. Like dpi, raising the bit depth also increases your file size, but gives you more colors, and better color gradations. Save in the lowest bit depth that suits your purpose.
Image formats affect file size, data quality, and viewability.
In other words, base your storage format on your viewer's capabilities. Images scanned into Adobe PhotoShop will automatically be PSD's. After scanning you can save your image as the appropriate file type for your needs. Good for line drawings and low resolution needs. Bitmap files can be huge, handling 16.7 million colors, and are frequently compressed.