i only read the OPs first question ..
You will never have a heart attack though it is very true that you can have flashbacks many years later as i have,,i used to used acid on almost a daily basis...and herd of flashbacks but didnt have any untill it was a few years later,,at first it scared me but then i just decided to go with it like it was a free buzz ...i was in a bank where they had thos sycoldelic floor tiles and couldnt stop stairing at them cause they were all swirlling and shit ,,,,so no big worries it happens,,,but also not to all,,i have since the bank incident had many more flashbacks ,,,just sitting in my living room watching the curtains move and shit ,,,i always just went with it ,,like i said it like a free buzz that doesnt realy last long at all,,so no worries ,,,keep yer chin up...