I would expect 5-8 years out of an average car battery, but generally closer to 5. I got 8 once by some magic.
Looks like it is a bit of a strange size, either an H4 or an H5. costco carries the H5 but only in an AGM for $180. Not sure if the factory battery is AGM or flooded. It's usually best to stick with whatever type the car came with as the charging voltages are slightly different.(AGM, flooded, or enhanced flooded in the case of start-stop systems that choose not to use a pricier AGM) not enough different that it won't work, but enough that an AGM would probably live 80% as long as it could have if it were in a car designed for one.
a bit of looking around and home depot has an exide H5 model for $129 at my local location. given the price its probably flooded
my hope is that the car can fit either an H4 or an H5, as the H5 is a bit wider and cheaper. from a bit of preliminary looking around it seems the SE came with an H5 and the LE came with an H4, but if there is a bit of space on either side of the battery, then the H5 might be designed to fit too.
If you go the route of replacing it yourself, all you need is a wrench, just remember one rule. you should ONLY put a wrench on the positive terminal when the negative is disconnected. This is because if you touch the wrench to the frame and the positive at the same time, it can short the battery and get that wrench very hot or worse, but if the negative is disconnected already, nothing will happen. If you touch the frame and the negative at the same time, nothing happens.
so when you disconnect the battery, disconnect negative first. if you touch the wrench to the frame, nothing happens. then once negative is disconnected you can disconnect the positive without worry.
when reinstalling, do it in reverse order, connect and tighten positive first, then negative. If you follow this rule, even if you are careless you can't short it out, unless you are really trying to short it out. also make sure to check that you are connecting properly before wiring it up, just in case.
after replacing the battery, you need to perform a "steering sensor zero point calibration" which needs to be done whenever the battery is disconnected. according to the service manual, you need to start the engine, drive in a straight line at at least 22mph for 5 seconds or more, then stop and turn off the engine.
my guess is that the lane tracing assist would be inoperable until it sees you driving in a straight line long enough to determine where the center is, and this procedure is just enough to do that.