will we get a 28% discount for upcoming pool party skins like other new skins?

You mean the discount that usually happens for 1350 skins for the 1st week or so?If so,most likely.I mean,there's no reason for Riot to not do that now.

Though like I said,it only affects the 1350 skins which are .Pool Party won't be discount since they will only be 975.

Yes we will, rioter Katey Khaos confirmed it here

http://boards.na.leagueoflegends.com/en/c/GD/dOZbxFAJ-kateykhaos-pool-party-question