Should I brush the algae of the rocks on waterfall? When I do a lot of it
washes into the pond. Dose this spread the algae?

I think you're fine.

It is tempting to full the algae of the roots of the floaters and other
plans, is this good or am I doing more harm the good. Is it OK for them to
be covered with it?

I think you can leave it alone.

What's the water temperature range in your area, winter to summer?

There are some fish that eat algae of this sort. American Flag Fish,
for example. I've seen it written that Chinese Weather Loaches also
eat algae, although that's a minority opinion. Good news is that they
aren't known to munch plant roots, really, so you could possibly put
a couple of these into your plant tank.

C//