You will find that the evangelical vote will be more conservative than the Catholic in each age, race ans attendance category.
As regards megachurches, I would say that they cannot be broadbrushed, but must be separated by type. The problem with Osteen type churches is that they owe their numbers to a saltless gospel of perfectly pleasing preaching, and others to Benny Hinn type charisma and counterfeits.
Then you have Calvary Chapel types, as well as 57% of megachurches being founded before 1961, in which more legit qualities may be are at work, and often demographics.
Could you post those stats? I'd really like to see the race breakdowns, particularly black and hispanic.
Thanks.