"Я говорю на нескольких иностранных языках." is absolutely correct, both lexically and grammatically.
Странный means 'strange, weird, queer, odd, unusual', it never means 'foreign'. Иностранный is a compound adjective formed from иная+страна ('another'+'country'). Странный is also derived from страна, 'country', but in a rather tricky way: first, the noun странник, 'traveller, wanderer' was formed from it, and странный is an adjective from странник. The meaning of странный developed from its original meaning 'pertaining to travellers, wanderers' in such a way: 'travelling' > 'from far-away lands' > 'of different culture, unusual' > 'strange'. Nowadays the connection of the words страна, странник, and cтранный is not obvious for an average Russian native speaker, and cтранный does not mean 'foreign' any more.
And ладно is not actually 'OK', it means 'well, if you wish...' or 'alright, I'll do it (so that to get rid of you)', it expresses agreement, often reluctant, and is used only as an answer, never inside a sentence. Ладно may or may not have the shade of reluctance, it depends on your intonation. The most neutral answer meaning agreement is хорошо, but it cannot be used in the question above, either. The Russian word that fits that question is правильно, 'correct'.