Unfortunately, I don't think that either one of those things would be particularly good for the game.
Extended death timer is a neat idea, however I can think of a couple problems with it. First, 90 seconds is a huge amount of time! End game death timers are only about a minute or so, and tacking on an extra minute and a half on top of that would be crazy. Remember, 2.5 minutes is 5 waves of minions! Second, if it added less time, it wouldn't feel impactful. There's still a lot of power to that, but it's harder to notice and doesn't provide immediate impact.
Stealing unspent gold isn't something I can see coming to League. Again, two problems: First, League, unlike DOTA, has income as a constant increase. That is, as the game goes on, your income only goes up, and so your power only goes up. (Notice that there is a tax for changing items, but this is a separate issue) Second, the amount that this could change the gold differential between teams would make it the most valuable thing in League. Consider a carry. Oftentimes they will have 1.5k gold before backing. Stealing this carry's gold would be the same amount of gold as two towers, as well as denying the carry about 10 WAVES worth of cs.
While both of these abilities are interesting, unique, and make thematic sense, I don't think that either of them is a good fit for league.