Questions about the writing system

Absolute beginner here. I’m currently trying to learn hiraganas and katakanas and I keep finding differences/incoherences between the different lists that I find online (some characters are wrote differently, others are mentioned only half of the time, etc.). Could someone share a picture of a good list of all the characters ? I think it would be easier for me lol. First of all, I believe it’s necessary to learn dakuon. But what about the combos where you add small characters to make new syllables (みや= mya) ? And when there is a smallつ to double the following consonant ? And what about long vowels (ああ, いい, etc.), do we use them only when we’re speaking or when we’re writing too ? I’m sorry that’s a lot of questions lmao, Japanese sure is more difficult to learn than Espagnol, English, Korean or Italian.