front control arm bushing (rear) - bad?

[yarikoptic]

80k 2014 outback 3.6R, Vermont (snow, salt, etc). I am in the process of changing driver side wheel hub and noted that rear bushing on the control arm looks not healthy to my ignorant eye: rubber separates from the middle bolt/spindle/whateveritis:



I (or wife who drives it usually) have not mentioned any noises/vibrations.
I wonder,

1. if I should replace that rear bushing while doing work there anyways (have a press, might need to borrow adapter), or such rubber from metal separation is "normal" and I shouldn't bother unless there are symptoms.
2. what part? I have tried to find the OEM part, which seems to be 20204AG011 but parts.subaru.com can't confirm fitment (will call local one tomorrow after they reopen). edit: according to www.subarupartsdeal.com search based on VIN it is actually 20204AJ020, so my initial search was wrong I guess.
3. is it ok to replace one but not the other (side)?

thanks in advance for the feedback