The difference between thu and sibh
I've seen this posted on a few sentences, so rather than answer it multiple times I thought I'd put a post up.
You use thu when you are speaking to someone you know or someone noticeably younger than you. It is singular, and never plural.
Sibh on the other hand is plural. You use it when speaking to a group of people, someone you don't know (especially someone who is likely older than you), or someone in a position of respect. For example teachers, parents, war veterans, doctors, ministers (you get the picture).
In everyday colloquial speech use of sibh is arguably on the decline. It's still very common, but several years ago people would have used sibh throughout a whole conversation and kept the formality. In modern day useage people generally make the switch to thu very quickly, which some people get annoyed about. In my old workplace we had a lot of Gaelic speaking customers and as a fluent speaker obviously I would converse with them in Gaelic rather than English. As I got to know them naturally I would make the change to thu, but the elderly in particular would tell me off if I ever accidentally used thu instead of sibh (and it is easy to do by accident).
I think the issue from a learner's perspective lies with the fact that English no longer uses the singular informal "thou" in most dialects. "You" in English is actually the formal.
To put it simply thu = thou sibh = you
You often see a suffix added to the end of pronouns.
Mise thusa esan ise sinne sibhsa iadsa
These are EMPHATIC forms. They are the equivalent to using an exclamation mark in English.
à and às are pretty interchangeable. The s in às is basically to make the whole phrase easier to say. I was born in Inverness and I say Tha mi à Inbhir Nis and would find saying Tha mi às Inbhir Nis hard to say. Similiarly, if I were born in Oban (for example) I would probably use às because Tha mi à an t-Oban is more difficult to say than Tha mi às an t-Oban.
I'm not sure if there is a set rule.
Also I edited the above post because I saw you posted a question about the emphatic form thusa.
à and às aren't interchangeable
à becomes às before the definite article
- Tha mi à Alba = I am from Scotland
- Tha mi às an Fhraing = I am from [the] France
(France is "The France" in Gaelic).
That's why it's "à Inbhir Nis" but "às an Oban" (NB not "
às an t-Oban" because we're in the dative case now).
It's also the prepositional pronoun [à + e], which is what it is after (most) interrogatives, (e.g. Cò às...?). Because.