Gridchin, that's a fine-loooking MK Sig. Congratulations! As far as the weight goes, get the widest strap you can find (at least 3") and you will get used to it. Part of the reason Alembics sound as massive as they do is the weight. So think of it as a good thing!
I have both Series I basses with the 3 position q switch and Series IIs with the QVC. I actually prefer the 3 position switch over the QVC for live work, as it's easier to find a tone on the fly. As others have said, the best way to get a handle on what the filters do is one pickup at a time. Roll the balance so that only one pickup is working. Leave the Q switch down. Play around with the the filter knob, going from one wide open (bright) to closed (very bassy). Then, do the same thing with the Q switch up. Then, roll the balance to shut that pickup off and repeat with the other. Then, repeat the process -pickup by pickup with both pickups on. You will get the hang of it fast.
By the way, the main difference between the Series basses and the MK Sigs (or any other Alembic) is the pickups. The Series basses use a wide aperture single coil pickup which are made hum-cancelling by the use of a dummy coil that sits between the 2 pickups (which is why some people think Series basses have 3 pickups). Your MK Sig (and all Alembics except for the Series basses) uses humbucking pickups. The pickups on your Sig are called AXYs. There are 2 different AXY pickups- the "regular" ones and the Fatboys. The Fatboys are wound to have a bit more bottom end to them. I have a MK Sig that began its life with 2 regular AXYs. I swapped them out for 2 Fatboys, but honestly it was too much... the bass wasn't punch enough for me that way. Now, I have a Fatboy in the bridge position and an AXY in the neck and it's perfect. But I also loved the bass with 2 regular AXYs, too.
Your MK Sig is an amazing bass and with a big amp at stage volume and new strings it WILL kick major ass.