Ok the first point is definitively good, a penalty should exist. About the tax 100 percent that's up to the user to decide will he accept or not, obviously I wouldn't necessarily accept someone lending me 50.000 SP but taxing me 100% for it, that would mean all curation rewards would go to that person. The ability to set custom "tax" is there in order to be flexible, someone would like to power up a friend by taxing him less so that the SP gain of the friend would be increased.

taxed you less, so you could possibly get bigger proportion of steempower as you would normally.

That is "desired", that can be used to power up good curators.