1. Not sure what the difference is between 6.1 and 6.3 versions, probably have to call 1st Texas on that one.
2. Starting in all metal wouldn't be the easiest way to start, it would be the hardest because you will be receiving a lot more information from that mode than any other mode.
3.Sens at 15 is ok for swallow hunting, like down to 3 to 4 inches. This may be what you want if you don't want to do a lot of digging. Set it higher for deeper targets like 6 to 8 inches. 85 is my deepest setting.
4. Tones, I like three tone best and I've tried them all.
5. Thres setting zero isn't to bad but I like +2
6.notching? 1st off it won't remember your last setting. As you turn the disc up it will notch out from lower to higher #s, you'll see above each segment as you turn the disc up a cursor will appear above each segment (iron,tabs,nickels,zinc). This means the detector will not pick up this type of metal. The way I set up is turn the disc all the way up to 65 and then go back and notch in each segments I want to pick up. Since I like hunting silver most of the time I don't notch anything but that's just me. Notching will take some practice, it's the most complicated part of the learning curve.