I've wrangled up the most interesting or relevant of his answers and prefaced them with the topic he was replying to:
[ On an increase to the rate in which players gain IP]: " ...there are no plans to change the standard rate of IP gains. Reducing the IP cost of content either permanently or through sales should help that IP work a little harder for you though"
[ On making all champions F2P to match competing games, such as DOTA2]: "As a player I preferred playing LoL over those games for lots of reasons, despite not having access to all of the champions. Fortunately, millions feel the same way. I think having players unlock champions provides both direct benefits (eg. more skilled play) and indirect benefits (RP purchases allow Riot to spend more on making the game better), so I have no plans to try to change that model. "
[On Global Ip boosts, such as double IP weekends] "I agree global IP boosts can be a great reward for players and can encourage more playtime. I'm exploring a couple ideas along these lines."
[On more frequent IP Price reductions]"I'd like to come up with a permanent policy tor IP reductions that players can rely upon, but am still gathering info to make sure we get the policy right. "
[ On the chance of getting skins for RP, something like 20k IP turned into 975 RP Skin]"If enough players wanted something like that, I could probably make it happen. But only if they promised not to call it a grind!"
[ On additional bundle options ] "I think there is so much more we could do with bundles, including themed bundles and some version of create your own bundles. It will take some time to make this happen, but I will start a specific bundle thread in the coming days as I'd like to get your feedback here."
[ On bundle prices being reduced if you already own champions in that bundle] "This is a great idea and the technology for it is already being worked on. I'll address this in the new bundle thread as well."
[ Additional question on "Pick Three Champions" style bundles] "Yes - there are some technical hurdles that prevent this from happening overnight, but everybody agrees it is a good idea."
[ On new things to buy ] "We are working on a few new types of (cosmetic) content that will allow additional customization, but I can't talk details at this point. "
[ On older 3150 IP champions receiving RP cost reductions ] "The long term pricing plan will address this."
[ On achievements and incentives for good behavior ] "There is a lot of focus here on achievements and rewards for positive player behavior, but it's not my area and I don't want to mispeak. All I will say is I fully support using pricing or special access to content as a reward for players who make LoL a better game."
[ On price reductions for Runes] "There are no plans to change rune pricing anytime soon. You have a good point, but players seem more concerned with rune page and champion pricing, so I'm focusing there first."
[ On why the new $100 RP price point is only temporary ] "It is temporary because there is a risk that it will prove too attractive for credit card fraudsters or create some other problem that I wasn't smart enough to see in advance. If no such problem emerges, and if players like having that option, we'll consider making it permanent."
[ On Riot continuing to expand in other countries and the use of different currencies ] "There has been a fairly steady pace of expansion into new countries and I don't see any reason for that to come to an end any time soon."
[ On the "one time refund" policy ]"Refund policies that make sense and can be implemented uniformly without being abused are tricky. Possible improvements to the policy are being discussed and you should hear more about this very soon."
[ On the possibility of a limited skin for big spenders] "You definitely have my appreciation and I like the idea of rewarding big time supporters with a special skin or some other reward. This hadn't occurred to me until this thread, and will take some time to plan and execute correctly, but please ping me again on this if it hasn't happened in the next few months."
[ On larger free champion rotation pools] "We have taken steps to improve the selection of champions in the rotation (glad you noticed!), but no, there are no current plans to change the number of champions. In our surveys, most players think the rotation works well today, and there are bigger player concerns to solve."
This is some very exciting news! New bundles, new "other stuff", and an overall better sense of what the community seems to want. I can't wait to see Hippalus roll out some more of his initiatives!