@DFT - I don't know that one so I can only tell you about the ones I'm familiar with and that I use a lot. I've never had this issue, but I can understand how it might occur and how it sounds.
First I get the mix right, with a decent level of headroom maybe -10db, it might be as simple as leaving it there, (without the maximiser) then I add the buss compressor, my goto is the bx_townhouse (just so the needle is tickled), then I follow that with the Waves L3 Ultramaximiser, again not much at all just to lift it to around - 6db, that combination really is stunning (I used to use the Waves SSL comp, and that's great too)
Depending on the Genre I might not use a maximiser at all, but nearly always a master bus comp.
As for your issues:-
1. This isn't good, that the intro sounds louder than the rest of the song, I think in this case I'd try it without the maximiser, Why do you need one on this song?
2. It sounds like your attack and release values are too quick, try setting them a bit longer.
I would nearly always use busses, especially when there are multiple tracks per tracking element, subBV, subRhyGtr, subBass, subSynth for example, the instruments go to subAllInstr, and the Lead vocal goes to subLVox, which might end up as a sidechain into a dynamic EQ on the subAllInstr buss...
Hope this helps
One thought...did you normalise the track on the master buss? that can lead to this.
If you send me the un mastered track as a wav I'll take a look if you want...
Hope this helps.