Since we're doing some shameless self-promotion here, I created a bunch of missions for a campaign I was running a while back:
Missions
Deployment Maps
I've tried to make these missions as fair and balanced as possible, without taking away too much flavour. Plenty there to suit at least some of your needs.
Not too sure what you mean by special rules, though. Do you mean campaign, mission or unit special rules?
Concerning unit special rules: In the first campaign I ran, players who performed poorly were offered credits as charity which they could then spend on
unit or army upgrades to level the playing field a bit.
For specific campaign special rules, I'd first have to know what type of campaign you have in mind. If you need ideas, I can give you one example which is a simple map based campaign I came up with, for which the
rules are very straightforward indeed. You'd only have to make some map, the design of which should depend on the number of participants and how long you want the campaign to go on for. Of course you could always add more interesting elements to it, if you want. It all depends on your gaming group, really. Mine tends to get distracted rather easily, so I try to keep things as simple as possible.