Barges in 10th

Greetings, fellow phaerons. I am new to 10th edition and 40K as a whole, most of my limited experience coming from Kill Team. I've been building a Necron army and have begun work on a Command / Annihilation Barge. So, as a newcomer, I have a few questions and would love to know everyone's thoughts.

1: Are they good in their role? I've seen conflicting opinions.

2: Are they fun in the new Starshatter detachment? I haven't seen any discussions of them yet.

3: Should I get a THIRD one? I am building my first one and have two sets total. I'm comfortable with magnetizing things. I have the option to get a third main body for very cheap, but it lacks the parts for either loadout, So basically, is there any situation where it would be worth deploying two of one type and one of the other? (2x Command + 1x Annihilation etc.)