Hi, my first suggestion would be the get started Tau box, good value and all the models have a use. I believe they are bringing out a Tau battelforce this Christmas as well, which looks like another good buy for your money, it has a Ghostkeel, pathfinders, Devilfish, commander, 3 stealth suits and a broadside.
So the get started box and that battleforce would be a solid start to any Tau army.
In regards to lists, it could probably do with some optimising. Hammerheads aren't generally considered to be great, although usable depending on what kinda game you are looking for. Don't put seekers on them, a blacksun filter and submunition rounds if you're going the railgun route. The smart missile system is the best secondary weapon choice. Alternatively, the skyray gunship is considered competitive and is a great support tank, if you like the look of Tau vehicles.
Don't put markerlights drones in fire warrrior squads or the shas'ui+ markerlight. Gets expensive and they aren't very tough. Standard fire warriors on foot, aren't great, aren't bad either (
IMO). An idea would be to take the DS8 turret for both squads.
Crisis suits with markerlight drones aren't bad, but generally the configuration is a commander (buffmander)with tanky gear, the buff gear and drone controller, in a squad of crisis suits with missile pods, target locks and marker drones. For this list, I'd split the 3 crisis suits into individual units and drop the marker drones.
For small games, fire blade is alright, or an ethereal.
In regards to marker support, either don't run it at this points level, or make the hammerhead a skyray.
Hope that helps. Frontline gaming have good articles on Tau tactics:
https://www.frontlinegaming.org/tactics/