Link aggregation

[Sad Clouds <cryintothebluesky%googlemail.com@localhost>]

I'm having a hard time finding informative docs on link aggregation.
NetBSD has agr(4) driver, but the man page is very skimpy.

I was wondering if anyone could answer some of my questions:

1. From agr(4) man page:

        The agr driver supports the following link specific flags for
        ifconfig(8):

        link0   Use the round-robin distribution algorithm.  Don't use
        it unless you're really sure, because it violates the frame
        ordering rule.
        ...

Don't use it unless you're really sure about what? If it violates the
frame ordering rule, what will be the end result: poor performance due
to driver reodering frames, or data corruption, or frame loss?

2. If I have a bunch of NetBSD machines with multiples NICs connected
to the same ethernet switch, does switch have to support link
aggregation protocol in order for it to work, or can link aggregation
work transparently across any ethernet switch?

3. Is there a limit to how many links can one aggregate together? For
example, if I have 8 quad ethernet cards plugged in (8 * 4 = 32 physical
links) will I be able to aggreate them into a single agr0 interface?

4. Does aggregation work with a single TCP connection? For example, I
aggreagte two 100Mbps links into a single agr0 interface, then I
establish a single TCP connection to transfer 10GB file. Will both
links be utilised, or only one?