1. Generally, yes. If the goblins are more likely to succeed at something because of an identified advantage, then you improve their positioning. If the goblins have insulated themselves from risk, then adjust the danger they face accordingly. There are two exceptions. Supplies (typically made in camp) grant an extra die to a single roll. You could rule that something the goblins are using to perform a task grants them supplies (noting that an extra die in addition to traits and titles is a rather significant advantage). The more likely case, when goblins have some a dominant advantage that putting them in a 'good position' isn't sufficient, is that they don't have to roll at all. The only have to roll for risky actions, if they have eliminated the risk of failure, there's no roll.
2. Yes, supplies grant an extra die in addition to a twist. I'm glad we covered this in more detail for issue 2.
3. TPKs can totally happen. The odds are generally in the goblins favor, but the dice system is such that every fight is a fight you could lose. They have to keep an eye on when to disengage and which risks are worth taking. Sounds like a fun session!