Dan M
We Give ourselves a Drop Dead Date of June 1st to have the corn in the ground - And we would prefer to have it in on or about May 15th. We usually start preparing the plots for corn by Late April (plowing/disking). Its hard because sometimes its so wet in Mid May.
We plant Beans at the same time - but if pushed - we can wait until Mid June to get them in, we would always plant the corn ahead of the beans if we were limited.
I've heard of others broadcasting corn with success - however I've heard it is ineffcient and only some portion will effectively germinate. You would need to "disk it in" - we like our corn at least 1-2" deep. You would want it broadcast so that it was 4-6" apart. I think you would have to expect thick spots and holes - but I might be worth a try.
Go with round up ready seed.
We get our standard seed products from the DeRuyter Co-op.
http://www.agwayfeed.com/deruyter.html
They are definitely "farm oriented" - not "deer flot plot" oriented - so I wouldn't go with out knowing what you want. What I mean is I wouldn't go in and expect or hope for them to help you with a food plot - they seem very busy there.
We get our clovers from Gander or Bass Pro usually - and we've tried some of the brassicas form there too.
Good luck this spring,
FH