Heh, I kind of ran into the chronology problem myself (AA4 vs AAI) recently, but had the decision made for me when my copy of AAI took a while to deliver (when I played it before, I borrowed it from a friend), so my choice was to either wait or play AA4 first, and I opted to not wait.
I think I like the tone of AA5 in general a lot more than AA4. AA4 got kind of dark for no real reason, and skimped on a lot of the characterization (or ignored it, in the case of Phoenix) and such that was so prominent in the earlier games. It's not a bad game, it's just clear they tried to take it in a very different direction. Much of that was changed in AA5, which seemed to allow the series to mature a bit while still sticking closer to its roots rather than veering off to the side. (I had a similar squee moment when I saw Ema again. <3)
For the shouting bits, are you holding down the button? You're supposed to hold down, like, Y or whatever to activate the microphone when Objectioning, etc. I didn't realize this myself until I saw Hubby playing; I never tried shouting myself, instead preferring to hit the buttons.