I foresee Groundskeeper completely changing the way you green. An uncontested Groundskeeper stack will beat a Province stack if given time to green, forcing your opponent to either rush the endgame or mirror you. I think the key to this card is knowing which pile to go for. You could simply use Groundskeepers for extra points on your Province buys, but they do offer the opportunity of going for one of the lesser VP piles. It might not always be viable to empty both Estates and Duchies - you junk yourself up so much that an opponent has time to build more and go for Provinces anyway. I suspect you'll need to be able to 3pile on Groundskeeper/Duchy/X where X is an engine piece/curse/whatever, then you leave the Estates as consolation for when you don't hit 5.
Temple has a few things going on. As a trasher it's quite poor. Early on it can get Copper+Estate, but mostly it will just trash individual Coppers (though it gets better with Shelters). The easiest comparision is Bishop, but it doesnt have Bishop's payload potential or symmetry drawback. At least getting VP for something you're gonna do anyway is cool. Donald X briefly explains the gathering mechanic here, though he doesn't specify whether the trigger to gain the gathered piles is the same on each Gatherer card. I'm guessing it won't be.
Chariot Race looks like a card you pick up early and often and then you just let it accumulate VP. Its cantrip nature makes this easy to do most likely. It's great with ways to manipulate the top of the opponent's deck e.g. Spy. It is, however, very hard to manipulate your own deck to block opposing Races. Trashing down super-thin is the most relevant way, but a stack of 6 Alchemists would do the trick (only two cards "cost more" than an Alch), and Stash can on the reshuffle.