Can rangers learn pickpocket and palm and if they can can they get any good at it, and do pickpockets suck at fighting?
You can't branch skills from subguilds if that's your question.
No its can rangers learn palm and/or pickpockit?
no
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If you want a ranger, and want one of those skills ("pickpocket" isn't a skill, but I think you mean "steal"), your best bet it to choose a subclass that gives you one.
If you're wondering what skills come with a guild or subclass, read through the descriptions. The don't say what the skills are explicitly, but in most cases you should have a good idea of what skills you might get and which you wouldn't.
Keep in mind that skills from subclasses won't be able to develop as much as skills you get from your guild.
Pickpockets have some weapons skills, so they might suck (at fighting) relative to warriors and rangers, but not compared to, say, merchants.
Three words:
Read. The. Helpfiles.