I think these two are more used on BrE. But I really would like someone to confirm. Are they used with the same meaning of the origianal ones 'guy, dude, fellow, man, folk'? Do they have a feminine counterpart or are they used for both genres.
'Lad' is still in current use, "I'm going out with the lads" for example. 'Chap' is very dated and rarely used these days.