arrays and block size

Hi,

I need to store a lot of int8 columns (2000-2500) in a table.

I was thinking about using int8[], and I would like to know:

1) is there a max size for arrays? I guess I could have 1 GB "worth" of values, but I would like a confirmation
2) there won't be any updates, only inserts and selects; since I will be using ZFS would there be any benefit in changing the block size (for example to 32K) in postgresql? Would it be better to use ZFS compression instead of postgresql's (TOAST)? That is: should I EXTERNAL for that array column and set compression=on for ZFS? I tried ZFS compression=on a 200 columns table and it worked faster than with compression=off...