And if you're too early to have Cursed (haven't beaten all 3 discords), but you've gotten at least one discord key, one HFHG key, and one of the two aa-rank keys, which are possible to get after a single discord (for example, raging forbidden dance floor), you can get that magic 110 difficulty as well.
That depends. Some say S4, as the max push death chance is lower. Though I prefer around S10…Yes, the max push death chance is higher, but with the detective duo team, you can get around 700% of normal damage, which can make fighting phases a bit easier…but that's been a long-standing debate.
Nobody in their right mind says S4, the people who do it in S4 have special reasons- they don't do it because it's sensible. The minimum "recommended" season would rightly be S10, as jimwormmaster later said. As anyone could tell you, "the higher the better", but going above S20 before you've finished r00t is probably wasting your time.
S10, although sooner, has a significantly lower Base Drain than 15 or 20, and although there are a lot of other sources of drain… considering the fact that +7 drain in juice costs around 100k PHRyo per day, and of course a chunk out of your juice limit, a few extra days of quality speedlooping can save you a lot in r00t. For this reason I would personally recommend somewhere around S15, but the right perms ('goodbye kitten' pink taser for example) can make a world of difference. At the end of the day, you should pick a season you like, as you're going to be in it for a while.
That, and in addition to the higher base drain, later seasons offer higher stat caps, which means it's easier to get around those nasty 35/40 checks for the discords, and the 50/50 and all later on, with less recompiling. And he's right, the right perms can be very useful. Boomstick for strength, Pink Taser and Pink Skull for help with focusing, and the K-Belt and Time Reversal Cube to dodge, should they actually hit you.
My first advice would be Get the hell out of Dodge Season 7- Seasons 5-9 are pretty much dead water for r00t, because of the ratio between Death Chance and Base Drain. Hopefully you're in the middle of speedlooping. Secondly, you want to grind up some levels- do it quickly and with focus, it shouldn't take more than a few days once you get to Jonin in the right season. Don't aim for level cap, but at least 30's will be quick, easy, and helpful with the discords. Make sure you have some good perms- forget about monster drops, but Mono and Wasteland completion as many times as necessary with Top Gear is pretty much essential. Make sure to complete (most) of mono in the season you are attempting it, it has a few non looping stat perms, and the reaper blood will be invaluable. There are various non-plot non-kai bonuses- halloween perms, Arena perms, Golden Items, Party House perms (mainly prize wheel as far as I remember), and Shop Perms. Don't forget to buy Counterfeit Permit from the shop again as it doesn't loop.
Hopefully a r00t candidate would have most of these (I think you probably do), so level grinding would be a good choice (again, don't waste time going too high), since it will last for as long as you stay in that season, but I'm just writing these things down to supplement the guide with a little more detail for those who want it.
It is my personal opinion that kai drops should be only a last resort for discord hopefuls, unless they lack Polar Star and/or Regalia. These two are very useful and will be needed for r00t progress anyway, so it's not too silly to try and buy them at a good price.
Not to mention that you need extra polar stars/regalia to upgrade to lost weapons, for r00t *and* PW later on.
I think the lightning strikes have something to do with charging the Flux Capacitor…maybe? It's been my experience that very little of BvS is just meaningless flavor text (apart from mission success/failure text, things like that)