Yes and no. If you speak scottish Gaelic you will notice that depending where someones from their Gaelic may sound completely different. This varies from area to area and is affected by the accent and the pronounciation. But generally its easy to understand on the whole. However if you attempt to speak with a person who speaks Irish Gaelic (commonly known as just Irish) then you will have great difficulty in understanding as it has evolved into a completely separate language. Some native Irish and Scottish speakers may be able to hold up a conversation, but learners will find this quite hard.
The Scots speak Gaelic.
It is reported that 94,000 people are native speakers of Irish in the Republic of Ireland; this is 2% of the 2011 population. As far as second language speakers the Republic is about 39% and Northern Ireland is 11%. All are bilingual in English as well.
Yes, Portuguese speakers can generally understand and communicate in Spanish due to the similarities between the two languages.
I suspect you are referring to Esperanto, first described by L.L.Zamenhof in 1887. There are in fact some 2 million speakers which is arguably more than can speak Welsh or Irish Gaelic or Gallego or ....
About 65,000 people speak Scots Gaelic, primarily in the Hebrides.
Yes, speakers of Spanish can generally understand Portuguese to some extent due to the similarities between the two languages.
No.
Generally, Mandarin Chinese speakers may not fully understand Cantonese speakers since the two languages are distinct and have different vocabulary, tones, and grammar structures. However, there may be some overlap in terms of basic vocabulary and phrases which could facilitate some level of communication between speakers of the two languages.
labhair a labhairt - to speak
They speak both. Irish (Gaelic) and English. Around 40% either speak or at least are competent in Irish. It is a compulsory subject in the Republic in schools. Monolingual Irish speakers are rare and usually found in Western Ireland.
English is blessed with many "registers," that is levels of correctness. At the top is the literary, Saxon dialect called Standard English. Many people speak this dialect at home, but many more do not. Standard English speakers are likely to complain when popular non-Standard forms are presented as correct.
They are related, they belong to the Latin language family.