I have some steel car bodywork that's rusty and wants treatment - mostly
exterior edges of wheel arches. I think the metal is good underneath, so
it's just surface rust.

On another car I treated this sort of thing by scraping off the surface
rust, treating with Jenolite, then two coats of Hammerite, then spray
colour. But the rust continued to spread. In that case I can't be sure the
rust wasn't just coming through from the other side, so nothing would stop
it.

I've been sanding off the rust with sandpaper and a sanding block, and some
good metal is coming up, but it's quite pitted and will take an age to sand
off all the good metal to make a flat good surface.

I've been thinking of using a wire brush in a power drill, something like
one of these:
http://www.toolstation.com/shop/Powe...ves/d80/sd1920

Can anyone recommend a type? I don't have a lot of space to work in, so
something small would be good - I'm assuming I want one with the wire at
right angles to the drill shank. How quickly do these get used up (ie do I
need to buy ten like I would sheets of sandpaper)?

I obviously need to wear gloves and goggles - is there any other protective
equipment I should wear when flailing? Are these wire strands as
dangerous as the ones you get from angle grinders?

Once I have bare metal, what's best to prime it? Use the Jenolite to treat
the surface? Or straight Hammerite? Or I've heard it suggested using zinc
primer (Zinc 182?), or an epoxy-based primer. I already have some Jenolite
and black Hammerite. This time I'd like to try using the manufacturer's
paint to get a colour match (a few bits are more conspicuous than undersides
of wheel arches, where I might just stick with Hammerite).

And for bits that aren't visible (not cavities), I've heard various
suggestions of using something like penetrating Waxoyl/Dinitrol, or just
engine oil. Anyone any opinions? The underside has already been
undersealed but the underseal is broken in places. I know this is
completely the wrong time of year to do this, but not a lot I can do about
that except copious application of the hairdryer... (or is it better to
leave untreated until summer rather than seal in moisture)?

Thanks
Theo