[FT] Fleet Book 2 questions

I have a few questions about Fleet Book 2.

1. FB2, page 4: ...any fighter carrying ship may only RECOVER fighter
groups equal to HALF its number of operational fighter bays in any one
turn.

When figuring HALF, do you round up or round down?  Or do you save the
fraction and carry it over to the next turn?

2. FB2, page 4 lists different fighter types.  I noticed that in an
earlier book, these types can be mixed and matched.  For example, you
can have a long-range attack fighter.  However, FB2 doesn't mention
mixing these types.  Is mixing the types not allowed any more?

Thanks.

--Greg