The tires might be out of alignment after swapping shocks, but I doubt it would be significant. I wouldn't worry about getting alignment right after.
Most difficult part of rear shock was reaching the bolts in trunk area. Otherwise a walk in the park.
I've swapping springs/struts on a bunch of different cars. The 318 is relatively easy except for compressing the springs. I had to hook one on the upper hat, and it was a little bid unnerving. Could potentially slip off. I saw posts about difficult aligning the strut, but I had zero problems.
- Attach 13mm x3 nuts loose in strut tower (easy with assistant)
- Slide (tap with hammer) 18mm bolt horizontal through top mount. May help to use floor jack.
- Attach (hand tight) bottom 18mm bolts switching between both to keep parallel.
- back out one bolt at a time, drop loctite, tighten
- tighten upper 18mm with loctite.
- tighten 13mm on strut tower