What the starting values and ranges of Tier and Status for factions?

What is the range of a Faction's tier? 1-6 or 0-6?

Mechanically, you could have a Faction of any Tier, if it made fictional sense. A Faction stronger than the Guild of Engineers, for example, would be Tier 6. The game comes with a Faction "board" that ranges from 1-5, so the GM would need to create Factions that go below 1 or higher than 6. A Tier 0 Faction would probably be a single ship of scoundrels, like the crew.

What is the range of Status?

The core book is oddly vague on this--it suggests +3 is the maximum for positive status, as that's where the crew can be offered their "endgame" mission. It's safe to assume that the Status range for S&V is meant to be the same as it was for Blades in the Dark: +3 to -3, where +3 is "Allies" and -3 is "At War."

What is starting status with a faction (if unadjusted by other choices like ship modules), 0 or 1?

Again, I'd assume S&V treats Faction Status identically to BitD. In Blades, "Neutral" Status is 0, so you can assume that's the starting point for all Factions in S&V.

The Blades SRD is useful for clarifications on the above.

I am one of the designers of Scum and Villainy. I'm traveling to a convention right now so this post from my phone will be a bit thin. I wanted to chime in and say most of KidDublin's answer here is on point.

Regarding the magnitude chart, you probably never need to consider status when you're thinking about magnitude.

We do talk about negative statuses in the book, but perhaps we don't make the range as clear as we could. It was intended that you read -3 as "At War" and +3 as "Allies". I think the sheets help make that more obvious.

Si poderia have a tier zero faction, but understand that players are unlikely to engage with those factions unless you make them. This is equivalent to a small crew of an independent ship - maybe five people. It's rare that you need to engage faction mechanics for factions of this size: if you make them mad, maybe they all show up on your next mission, but since your next mission is likely to be off-world, they might not even have that option. A crew quality of zero is equivalent to a tier zero faction's gear (though it's worth saying that crews are not factions and that's only for discussion with respect to position.

Hope that clarifies! Thanks to @yorkist for reaching out to me on Twitter. If you have more questions, I'll check back in this thread, or you can hit me up on Twitter: @worldnamer.