It sounds like you are new to scanning. Hope this helps.

1) With any high res scan, choose to save as Tiff in the maximum bit depth that your editing software will handle. Probably 32 or 48 bit. With black and white, 16 bit is sufficient.

2) You must decide what size scan you want to produce before you set your resolution and output size. I find that a high resolution setting (say 1200 dpi) works best if you keep the output size the same as the original. If you want to set the output size larger than the original (say 8x10) I find that a resoultion of 600 dpi works best. If you are making a 20x30 then 300 dpi works well. You must balance file size with your scanner's actual ability to scan high res. Most scanners don't scan at high res and enlarge well at the same time. Your setting is 5x7 output so I would use 900-1200 dpi. You can compare it to 2400. You may find that 2400 is not as sharp. Trust me on this.

3) Sharpening - Use unsharp mask. Don't oversharpen.

4) Digital Ice - Uncheck. Clean your neg with an Ilford antistatic cloth instead.
Dust removal - Uncheck. Grain reduction - Uncheck

5) If the neg is contrasty use the 16 bit black and white setting, but if the neg has a wide range of tones scan it in color mode. You will convert it to plain grayscale in your editor. Doing this gives you more detail and better tonality.

6) Adjustments - This is where you make it or break it. Your basic settings in Epson Twain are easy to use. Remember, you want to preserve your blacks and whites not just adjust for midtones. You will need to experiment because the scanner's ability to scan black is limited. The scanner will not give you deep blacks.

A suggestion: After you get comfortable with the basic twain interface consider upgrading to Silverfast for your scanner. Silverfast is better for negs and slides. It is also more complicated.

Things to remember: If you make a low contrast scan you won't have much to work with in lightroom. If you make a scan with too much contrast you will lose your shadows and highlights. Contrast is very important.