You don't have to check for all of those things. Only if your a bean counter from Nerdville. Bu I have to admit, I checked 30 save files.
I never found all the items in 1 game. 2 out of 3 rune farming items on the first 5 islands is possible. My current game is without Well of mana or the Shield of Rekross, and the Gladiator Sword is far away in Reha.
The list of units is also not compulsory: it speeds things along to have strong units early on, but you don't need all of them. Heck, you probably do fine without any of them.
Knowing the scroll locations are just convenient. I find finding Phantom, Sacrifice and Turn Back Time near the end of the game very unconvenient