What are the implications of the Find Familiar and Find Steed spells changing the creature type from Beast to Celestial/Fiend/Fey?

The Find Familiar and Find Steed spells both have this sentence describing the creature type of the summoned creature:

The [familiar/steed] has the statistics of the chosen form, though it is a celestial, fey, or fiend (your choice) instead of its normal type. (PHB 240)

I’m wondering what implication choosing celestial vs. fey vs. fiend for the summoned creature would have. I have three things I’m specifically interested in listed below.

  1. Is a familiar visible distinguishable as the type of spirit? For example:
    • A wizard with an allergy to cats conjures a hypoallergenic fey cat sprouting soft grass instead of fur
    • A tiefling paladin conjures a fiend warhorse steed to have a coat colour resembling a Nightmare
  2. Does the type have any effect on the familiar’s alignment? For example:
    • Inheriting the alignment from the creature’s stat block (unaligned in most cases) seems like the most direct option but would a celestial imp still be considered lawful evil?
    • If you command your fiend cat to sit on someone it may choose to painfully knead them whereas a celestial may be more relaxed and cuddly.
  3. Does changing a familiar to a new form allow it to change the type of spirit?

    If you cast this spell while you already have a familiar, you instead cause it to adopt a new form. Choose one of the forms from the above list. Your familiar transforms into the chosen creature.

    Adopting a new form sounds like it remains the same kind of entity. Does this mean to change the familiar from fiend to fey would require summoning a new spirit and therefore be treated like a new NPC?

These are grey areas in the rules, I am looking for official guidelines or other credible sources that can help me make an informed decision on how to rules these as a DM.