Regarding Boots of Speed, I've noticed for my berserker/mage or fighter/thief (as well as NPCs like Minsc) if they have 3 1/2 attacks, once they put on Boots of Speed, they now have 4 attacks and walk slightly faster.
Unfortunately, I am not familiar with the advancing rules, therefore I cannot comment on the attack rates at lvl 19.

As for the lvl 50 exp cap remover, I've got mine from:
http://www.sorcerers.net/Games/BG2/index_editors.htm
Never really figured out if it was working properly though, my primary intention is to take out the exp cap.
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Long live H22A1!!!!!