Personal pronouns in Irish

This one just for reference.

In Irish, I is MÉ, or if a special emphasis is needed, MISE.

When speaking to one person, YOU is TÚ, or if special emphasis is needed, TUSA. The object pronoun ("thee") is THÚ, THUSA, but note that the th- can be delenited back into t-, if the preceding word ends in D, N, T, L or S (mnemonic: "dentals"). I'd say this delenition is most typical of Munster Irish. THÚ is also used in such copula structures (classificatory ones) as Is múinteoir thú "You are a teacher", but note that in identification sentences such as Is tusa an múinteoir "You are the teacher", there is no lenition. This applies not only when there is an is, but even when it is omitted: Tusa an múinteoir.

Third person pronoun for men is SÉ or emphatically SEISEAN, for women SÍ or emphatically SISE. But in copula structures and in object position ("him, her"), the initial s- is dropped:

is eisean an múinteoir "he is the teacher" (also eisean an múinteoir)
is múinteoir é "he is a teacher"
is ise an múinteoir "she is the teacher" (also ise an múinteoir)
is múinteoir í "she is a teacher".

First person plural in Irish is basically SINN, emphatically SINNE. However, the original verb ending -mid has turned into a pronoun, MUID, emphatically MUIDNE (also muide) and is today more common than SINN in subject position: thus, we say chonaic muid é "we saw him", but chonaic sé sinn "he saw us". Note though that chonaic sinn é is not wrong, although it is probably so marginal that people not familiar with a dialect where it is common usage might feel it to be wrong. My personal impression is that chonaic sinn é is typically Northern Mayo Irish.

Is there such an object form as INN? Yes, there is. However, this form is seldom seen in written Irish (it isn't very common even in folklore volumes), and must be seen as substandard or dialectal.

Second person plural - you people, you all, you guys - is SIBH, but note that it is pronounced as if written sib in much of Connacht. The emphatic form is SIBHSE, again in Connemara pronounced sibse. Dropping the initial s- to signalize that it is an object form is again marginal dialect and will be perceived to be out and out wrong by those not familiar with the dialect concerned. And to use ibh(se) as a subject form would feel grotesque to the extreme, although there probably is some recorded dialect (or some half-forgotten Doegen record) where such a usage exists. 

SIBH could be used for addressing one single person in older Irish - the way they still do in Gaelic Scotland - but this is definitely an obsolete usage in today's Irish. The only remnant there is, is found in Ulster Irish, where they might still address the priest as sibh. Well, at least this is a usage Séamus Ó Grianna has recorded in his short stories.

Third person plural is SIAD, emphatic SIADSAN, object form IAD, IADSAN. What I said about the third person singular pronouns applies to the plural pronoun too: you CAN say tá iad ag obair instead of the standard tá siad ag obair, but that is a dialectal or colloquial usage. On the other hand, you must not use siad(san) instead of iad(san).