Questions about best practices w.r.t. writing a kernel module port which modified LinuxKPI (BATMAN)

Hi!

I worked on porting the batman_adv Linux kernel module to FreeBSD
using the LinuxKPI last year as part of a GSoC project and I now have
time to work on WiFi support for it (which is necessary for it to
actually be useful in practice). Before I do so though, I'd like to
create a port for it. I have a few questions about best practices
w.r.t. going about this which I was unable to answer by myself by
looking around at other ports (specifically drm-kmod, it's the only
other port that I know of that distributes a kernel module that
depends on the LinuxKPI). Here are the two main questions I have:

1. I have made changes to the LinuxKPI headers and other parts of the
kernel in order to accommodate batman_adv. Is it okay for me to
upstream those changes, or should I expect users to apply a patchset
on their kernel source and to recompile it? If I can upstream them,
what should I do about older versions than -CURRENT? Will I just have
to wait for those changes to go into the next -STABLE release? And if
so, will that mean that any updates that I make to the LinuxKPI
headers necessary for newer versions of batman_adv will either have to
wait until the next release or be distributed alongside the port?

2. I have made changes to ifconfig to support the creation of BATMAN
soft interfaces. Should I upstream those changes and somehow disable
them when the kernel module is not loaded, or should I distribute a
patched version of ifconfig with my port? Or should I go with a
different solution entirely, and write and distribute a tool similar
to batctl (which from what I understand was the route taken when
distributing BATMAN on most Linux distros before iproute2 added
support for managing BATMAN interfaces)?

Thank you so much in advance for your answers & help!

(Warner, John, I've CC'd you two as you were in the thread on the
possibility of upstreaming this to the source tree.)