Hi, 2 short questions:

¿Is the unofficial patch directly installed? just run the game and play?

¿Is there any translation to spanish?

TIA

I don't know if there is a spanish translation. You should check on Nexus or ModDB.

For the unofficial patch, the GoG version of Bloodlines comes prepatched with the basic patch. That is mostly just bugfixes and the exe and dlls adapted to modern computers. So if you want just that you're good to go with the game from GoG as is.
If you want the changes and restored content from the plus patch you have to download and install it separately. You can get it on Nexus and ModDB.

One thing is important, though. If you install any mod, don't use Galaxy, or at least disable auto update. Otherwise Galaxy will restore the version from GoG on the next launch and that will corrupt your savegames.

If you need more info visit planetvampire.freeforums.net There are some spanish people as well, who can probably tell you if there is a spanish translation.

Spanish translations for older patches exist and can be found on The Patches Scrolls.

I don't know what the clan dlan version is, if you mean the Clan Quest Mod, it has it's own UP build in. And you are right, the last Spanish translation of the UP is so old that it isn't mirrored on The Patches Scrolls anymore...