Al Reynolds wrote:
[...]
For (b), [plants to retain soil inthe bank] I had thought about
just grassing the bank, but I'm
wondering if anyone has any suggestions for plants which
will do a better job of "matting" the surface of the bank together?

I'd say that grass, though a bit dull perhaps, would do a better
binding job, and do it quicker, than pretty well anything else. You
can grow a lot of low-growing wild flowers such as primroses in it
for variety. If you use grass, then convenience and safety of mowing
will be the real decider for the angle of the slope. I want to stress
safety he not just the potential for the more obvious dangerous
accident, but longer-term considerations like strain on your back.

So if it's within the budget, a good collection of ericas or heathers
would be very attractive. Once established they'll hold the soil well
enough, especially if you lay down a landscaping mesh; and would need
serious weeding only for the first two or three years; and would
never need mowing, of course! You'd have to be prepared to shell out
a pound a plant, though, unless you could find a bulk source.

Mike.