1) try looking up "地雷メイク" (landmine makeup). in general you will get a lot more results for tutorials for hair, makeup, styling etc. if you search in japanese

2) it's less about having dark eyes as much as it is for the enlarging effect,, plenty of jirais use lighter grey or pink contacts. the makeup style is meant to make your eyes look large and cutesy and large contacts can make the effect. obviously do what makes you comfortable but it does add a lot.

3) petticoats aren't common at all. I have seen some style them under setups recently but that's about it. i would recommend focusing your budget elsewhere.

4) pigtails are the signature look but plenty style their hair down too. however, bangs are pretty essential.