Chichewa

Yes — they're two names for the same language. Chichewa is the term used in Malawi (where the Chewa are the largest ethnic group); Chinyanja is the term used in Zambia and Mozambique (where Nyanja is a related ethnic-cultural identifier). Linguistically, the two are mutually intelligible varieties of the same language with minor regional differences. The dual naming reflects national-political identification rather than linguistic divergence.

Malawi as the national language (where it's spoken across the country), plus eastern Zambia (especially the eastern provinces), Mozambique (Tete and Niassa provinces), and parts of Zimbabwe and Tanzania. Chichewa serves as a regional lingua franca for tens of millions of people across south-central Africa, alongside Swahili in some northern regions and English as a former colonial language.

Not in the European sense, but it has Bantu-style noun classes — about eighteen classes that mark different categories of nouns and drive agreement throughout the sentence. The noun classes function similarly to grammatical gender (in that they determine agreement) but operate on different semantic principles, distinguishing humans, plants, things, abstracts, locations, and other categories rather than masculine/feminine.

Yes — Chichewa distinguishes high and low tones, both lexically and grammatically. Tone shapes word meaning and signals grammatical distinctions like tense, aspect, and clause type. Tone is not normally marked in standard orthography, which can make tonal contrasts invisible to learners reading written Chichewa. Listening carefully and learning tone for each word is part of the curve.

Both are Bantu, but in different branches. Swahili is in the Sabaki branch (East African coast); Chichewa is in the southern Bantu group. They share Bantu structural features (noun classes, agglutinative verb morphology, similar phonological inventories) and core cognates from common Bantu roots, but they're not mutually intelligible. Swahili has heavier Arabic loanword stock, Chichewa has more Portuguese and English influence.