As you are getting used to flying the new bird, now you get to learn its systems and how they were put together. First thing you will discover is that each experimental plane is unique in their build and systems. Hopefully you received schematics, builder notes, and component manuals with the purchase.
For the Amp meter readings, the first thing you should check is how and where the sender (shunt) was installed. There are 3 different ways to install these and gauge indications will be dramatically different for each. Check your installation manuals for this.
Tach issue might be as Carl described (& is common issue), but it could also be an instrument set-up issue. Check the Advanced installation manual for proper settings for your engine & ignition pulses.
Good luck & good flying your new bird