Congrats on the new detector! You picked a great detector - ironically I traded an Ace 250 to get my Silver Umax that I use almost every hunt. I have never regretted that trade for one second. You will do well with the detector, and as with any detector - it will take you a little while to get good with it. You will dig junk sometimes, but as you get better - that will taper off as well. I am now able to use my Silver Umax in trashy parks and dig like 80% good targets - just by the sounds and where it knocks out on the discrimination.
With some practice you will be able to identify your targets easily. What I do is this: Detect at low discrimination, just above iron. Swing until you get a good - smooth repeatable signal. Lift the coil up a bit to get an idea of how deep the target is. (deep targets will be obvious) Use your thumb to scroll up the discrimination until the signal barely starts to knock out. That will tell you approximately what your target is , and how deep.
I can't say enough about the value of this detector. You have a lot of fun ahead of you. Be proud that you have all that performance and only had to pay not so much . . . I'm not so sure you need that 5.75 coil on it, b/c that 8" stock coil is sweet - but then again I haven't used the 5.75 on the Silver. Let us know how that smaller coil works out I haven't read many comments about it- I may pick one up myself.
If you have any questions about the Silver Umax - one of us in this forum has the answer,
Good luck
Ian