「いいとこまでイケた」 literally means "I was able to go far enough." That in turn means "Something went adequately well." So. you got this one down.
「何でも」 here means "I am told", "they say", etc. It does not mean "everything" or "anything". ← Very important! It often gets translated incorrectly in fan subs.
「ツンツンと」 means "in a bad-tempered manner"
「ヘタれる」 = "to get exhausted"
「デレる」 = "to act affectionate"
「好感度」 = "popularity rating"
「大幅アップする」 = "to skyrocket", "to increase by much"
My own (mostly literal) TL：
"However, I tried to do just as my dear master told me, and it actually went quite well! They say that looking nicely exhausted and acting affectionate after doing all sorts of brutalities (in a bad-tempered manner) will make that thing called 'popularity rating' skyrocket for you, right?"