You definitely can't learn Thaumaturgy without a teacher (even Tremere need someone to teach them, to raise Thaumaturgy in any way, and besides they try to exterminate anyone else they catch knowing it), but all the others are certainly possible.
This would/will be a GM call. Which will be made on a case by case basis as necessary.
The physical Disciplines (both in oWoD and nWoD) require no actual teacher. For a Caitiff to have a Clan Discipline as a starting discipline, the Caitiff in question would have to have a Mentor of said clan with abilility.
As for Thaumaturgy, it's lost to all but the Tremere and a few other distinct Bloodlines of Independent Clans and what is left of the Manus Nigrum.
Again, GM call. Caitiff, according to my copy of the main book can start with any set of three Disciplines approved by the GM. As for Thaumaturgy, long story. Suffice to say that any world plot stuff White-Wolf did post 1998 can be ignored.
The book of Outcasts: Players Guide to the Pariahs is a Second Edition material and as well, it was disbanned and concidered "voided". The more recent book on the Caitiff and their Thin Blooded relatives are that of "Time of Thin Blood".
Given that I own Outcasts and do not own Time of Thin Blood (see above response), this statement is null and void for any WoD game I run.
It's voided because the Time of Thin Blood rules balance the previous one out. Caitiff still have it easier when coming up with new Discplines, just, they changed the system.
See above two responses.
I think the default three Disciplines for Caitiff are Potence, Fortitude, and Presence, but it varies (somewhat) with the individual...
Caitiff choose three Disciplines, of the player/character's choice, which become "clan" ones for the individual. The only limits placed on the choice are the individual GM's. In part, this is because any
Kindred can be a Caitiff, if (s)he doesn't know anything about his/her sire.
Panders are not in the Sabbat they have the same disciplines
Nope. Panders and Caitiff are identical. THey're just organized under the Sabbat, versus being unorganized under the Camarilla.
are you reading the same Guide to the Sabbat I am? It says clearly that the Panders have no fixed Disciplines, and are for all practical purposes Caitiff. Did a later book change this somehow?
Nope, there's been no change, at least to the best of my knowledge. And given that the book is no out of print, I doubt it'll be changing. :)
Anyway. I'll put in the request for a board by the end of the weekend, once I polish a few more little things (around school work and housework).