Your rental house will likely have a standard package ready to go. And, unless you have preferences for equipment, or specific needs, this may work well for you.
I've slowly been converting myself over to Sachtler sticks, as the head comes with the package and is usually sufficient to take the weight of a basic Alexa package.
Previously, and still when I rent large camera packages, I stick with the Ronford or Oconnor sticks and heads.
You didn't say which Alexa you were shooting with, so I'll assume its not the Mini, or Studio.
When you get the Alexa, in the box should be the following:
Arri Alexa HS Camera w/ EVF-1 Electronic Viewfinder
2 vf cables (Long, Short)
Center Camera Handle w/ ext.,
12v accs. cable.,
bridge plate adpt.,
v mount adpt,
19mm bridge plate,
2x - 24v power cables,
Audio Y cable,
2gb sd card,
AB Tandem 150 ac/ps,
If you plan on doing any filter work, you'll need a matte box which will come with its own accessories. I would go 6x6 personally, but I like big cameras.
The MB-14 4x5 box is excellent too, and not too large.
The rental house will provide you with a set of lenses, your chose based on availability. If shooting Anamorphic, there are 4:3 sensor Alexas available.
A selection of 19mm rods
Since you seem to be a 1st AC, you probably have your own preference about follow focuses. There are many, they all work the same. Always get a hard follow focus, manual - studio style setup. I can't tell you how many times the wireless follow focus has crapped out in the middle of a shoot. I've seen prestons laying apart in pieces with AC's and flashlights trying furiously to get them to work more often than they work. Arri FF IV with Whip will save the day. Better to have it than not.
If you require a focus monitor, get one. SmallHD is not the only, or the best brand available.
I ALWAYS carry Anton Bauer Cine VCLX Battery w/ chgr, chgr cable, accessories. This is the big blue box battery that weighs many pounds. My AC's love to change out those Gold Mount Cine 90's or whatever we happen to have, which is great for hand held or stedicam work, but when I'm on sticks, just get me the big battery - I hate changing batteries. Panavision sends THREE of these with each camera no matter what. Your rental house will likely include these by default.
The rental house will also include plenty of mags - usually 8 or 10 media cards appropriate for the camera. Most of the Alexa line can be setup to use SXS cards, unless you have a different workflow - in that case please discuss your needs with the rental house.
As far as LUT's go, if you want to go Teradek, they can load luts on the teradek and display them on the DP or Director monitor. I usually travel with a production monitor that can hold LUT's in and not worry about the Teradek because its menu is wonky. While you CAN do it, I'll recommend you go to Arri's website and look that information up yourself if you want the camera to do it - you'll need to know how to navigate the menus yourself anyhow.