All right, so I was thinking, what would the general tactics and weapons look like? (I'm assuming a situation where one side has pretty much complete domination over orbital space - cause, unless you're really in a hurry or something goes really wrong, you won't even atempt a landing before achieving that. Also, I'm assuming it's the Feds who are attacking (with the intent of taking somethimg, not just blowing it up), not some immoral, mass-murdering empire).
First the defenders:
- Well, given those superpowerful sensors, obviously the first thing you'd want is to avoid detection. Even if the enemy does know your general location (you're protecting a fixed asset), you'd want to deny him as much information as possible. So - sensor jammers, dampening fields, false sensor emmisions, natural interference. I assume that with a big enough device (or a solid number of them) you could cover maybe even an entire city.
Then again, since you can't exactly jamm visual observation, you'll also want to get out of the open and use some good old fashioned camouflage (or if you prefer something more high tech, holograms). Urban and wooded environments will obviously be a good choice. Maybe a few smoke screens (though, given how advanced their weather control technology is, smoke and adverse weather, like clouds, could probably be dealt with by an invader).
- When the enemy does know where you are, you need some protection from his fire. Shields, even huge city-covering ones, would probably be used, but given that you can pound them from orbit with impunity, they would be just a way of slowing down the enemy. Actually, smaller shields used in ground forces combat could prove more useful, since they would be harder to precisely hit from orbit.
Aside from shields, you'd probably also want to dig your positions as deeply under-ground as you can - or if you are sneaky, put them under or mixed with civilian-populated areas. I assume a simple building is enough to protect you from the starships phasers stunning effect?
- Restricting enemy mobility. Transporters are enormuosly powerfull (and not just for mobility, but also as weapons - you can easilly beam your enemies out of the way), So - transport inhibitors and scramblers, in various shapes and sizes, scattered around your positions. If it's possible, maybe even a small personal transport inhibitor for every soldier.
Sensor jammers could prove enough, though, cause I'm not sure transporters can really work without precise sensor information. Some hidden and highly mobile (cause, the moment you fire, the starship in orbit will pretty much know exactly where you are) surface-to-air systems for shooting down enemy shuttles.
- Your own mobility. Well, obviously, you can't move in the open. And like I said, you need it badly. So, hidden, camouflaged tunnels and paths, perhaps vehicles. Transporters (your own jammers could prevent this, though - can you beam or scan through your own interference? maybe use landline-connected fixed transporters to avoid the interference?).
Come to think of it, if your countermeasures are working, it's not really that disimilar to modern combat. Or I'm just too unimaginitive?
P.S. Yeah, I definitely think too much about these things.

And there's more to come!