Technically, yes, but it would be better to download the whole thing if you have a regular wow account. The trial client is a streaming client, meaning that not everything is on your computer. It will be a lot slower, laggy, and things will take even longer than they normally do to load.
A trial account itself is not the issue, it's the installed program (client). Once you have that installed, and you have made an account with a private server, it will work regardless of you also having a trial account at Battle.net.
Yes.
No, once a trial account has been upgraded to a full account, you can not go back to using it as a trial account. If you want to do another trial account, then you need to sign up for a whole new one.
Go to the official site linked below. Create an account. Add WoW or a WoW trial to your list of games. Download client. Log on with your account, and create your character.
If you have the full game downloaded into your computer, no. All you have to do is make the trial account and when it says to download it dont, and just get on your trial account.
Yes I would believe so.
Yes, you can use any addons that a full account can use. There is no limit.
No you can't, only 10 day trial work on wow (steam)
trial version of the game does NOT work for WoW private server BUT you can download the game content for free you just can't play retail unless you buy it
There are trial accounts that allow you to play for 10 days to try WoW out but that's it.
Yes, you should be able to play the test realm/client using a trial account.
It can take several days after you finish processing the upgrade. Give it a few days.