Is there a single word/term for crutch words, that people often use in speech?

if you mean uh, um, er, and so on, these disfluencies are commonly referred to as filler words, or fillers. there are other sorts of discourse markers such as "oh", "well", "now", "then", and "I mean" and discourse particles such as "you know" and "like" which may also be referred to as fillers.

maybe jim, our resident linguist, will drop by and clarify these usages.

thank you very much for that. I was indeed referring to the likes of 'you know' and 'like' (discourse particles). I think I did come across a single word for such usage. It's completely possible, though, that I am imagining things. I sincerely hope jim will drop by and give his expert opinion.

will drop by and clarify these usages

Looks like you've done a goodly job on your own. You might want to read up on discourse analysis (and rhetoric or pragmatics).