I think the simplest fix is to take the rule FFG already uses in IA to address this exact problem:
If the opponent has more remaining activations than you, you can pass.
That lessens activation pressure (the n+1 activation has less value to a list) and greatly increases the value of large ships (because you can always delay to go last, so they don't get as horribly outmaneuvered). I think this would need to be playtested, but is likely to be a positive change for meta flexibility and the game.
I don't think that's a good idea. Demolisher is strong enough as it is. First player would just keep passing until they had last activation. Having lots of activations is a fleet build choice, you give up fancy expensive stuff, it's a trade off. Personally I don't see any problems with the activation game as it stands.
if you are going to pass, you cannot have last activation since you have to act when you have as many activations as the opponent. The person with more activations ALWAYS has last activation, they just don't get the last 4 activations if they have 4 more two point officers.