Questions about adding a trial key to existing account

For the sake of discussion, let’s say I only have the Nightfall campaign and wish to add a Factions trial key to my account.

1. Would it be possible to add a new trial key (either Factions again or another campaign) at the end of the trial period? No
2. Will I get extra character slots to create the trial characters? No
3. Can my existing characters from Nightfall move onto Factions? Yes
4. Do trial characters have access to the Guild Hall? Yes
5. Is it possible to unlock Factions skills via the Priest of Balthazar? No

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* Edit: So I tried this out and updated the answers for anyone who might search for this thread.

Trial keys are only proph if I remember correctly. And I'm fairly sure they can only be used on new accounts and no reused. So it negates questions number 3 and 5.

And trial character do have access to Guild Halls.

* Can my existing characters from Nightfall move onto Factions?

Yes, they can.

* Do trial characters have access to the Guild Hall?

Do you mean an existing Guild Hall? Yes. If you mean can you create a Factions-only GH, I don't know.

* Is it possible to unlock Factions skills via the Priest of Balthazar?

AFAIK, yes, but you will lose access to those skills when the trial expires.

Not true. The online-accessible trial is Proph only, yes, but there are trial keys for other campaigns than just Proph. My NF box came with a trial key for Factions (or possibly Factions+Proph). There are trilogy trials, called GW starter packs, but I'm not sure if they can be used on existing accounts or only new ones.

I don't think you can use more than one trial key (of the same type) on one account - otherwise, you could just keep playing by using trial keys instead of buying the campaign.

Keep in mind, if you bring a non-Factions character to Factions and he remains in a Factions outpost while the trial expires, you will lose access to that character until you buy the campaign.

Any other warnings / restrictions about trial access? (Other than the ones listed on the Guild Wars website)