The whole analogy of the faithful and discrete slave is that Christ returns and decides from the actions of the slaves who is the discreet one and who is lazy one or whatever. The idea isn't that one of the slave declares himself discreet and faithful in advance - then when Jesus returns he says - "Hi Jesus, I'm the discrete one - just so you know. He's the haughty one, I'm the discreet one - so i'll have my reward now thanks."
Jesus decides. The slaves aren't even aware of any future reward. (that's if you take the parable for a parallel with our times - which is a ****ing stretch to begin with.)
By saying that they haven't been rewarded with all the belongings yet but once Jesus returns, is I think from their prospective supposedly 'humble' (which shows how out of touch they are). In reality they are outlining the terms and conditions to Jesus, saying "Sooooo... When you're back and find that we are the discreet slave (because we declared ourselves such) we'll be happy with dominion over the earth and heaven... I think that should be sufficient reward - cheers."
I think it was a talk by Stephen Lett (pre new light) who said something along the lines of angels in heaven not getting peeved off when the newly appointed annointed kings take on a higher position than the angels - the angels will show a humble attitude to their new masters (I'll try to hunt down the exact reference)
The generation thing is obviously to buy more time.
I would hazard a guess to the Faithful Slave thing to being to get the R&F to disregard anything that the annointed say to them. For example, we had an annointed brother in our congregation and the bro's and sis's viewed him as having some special insight on things unwritten. He never said anything out of line that I can remember but I can imagine annointed bro's saying things and the R&F taking it as if it were coming from Jehovah.
144,000 are no longer the faithful and discreet slave? Strips them further of the little power they had in the congregations (rememeber mentally imbalanced anyone?). Who knows, they may do away with 144,000 altogether in future - and 'discover' that 144,000 was symbolic for 8.