As far as I know all droids in Star Wars have free will.

Han Solo gambled and won the Falcon from Lando (who appears well off), it was definitely too expensive for him to have bought normally.

I think the hyperspace battering ram is funky, but I believe it was less that it was a good tactical idea and more of the First Order being extremely arrogant by not having their shields up, not using a tractor beam, and not just sending a smaller ship forward to close the gap and blowing it up.

I think the movie wanted to show that they were savoring the victory and were willing to draw it out as they believed the rebels were drowning in hopelessness.