How to specify custom DH parameters?
When using DH ciphersuites, there are necessary DH parameters, if they are not specified explicitly, default ones are used. There is a default set of 1024bit parameters.

Also, is there a way to specify ECDH parameters for ECDH ciphersuites? (This is less important than DH, though.)

The FAQ of this list (http://httpd.apache.org/docs/misc/FAQ.html) is a 404. Search function for mailing list archives did not take 2 character keywords (DH), they were ignored.