Must Ukrainian citizens fleeing the war obtain refugee status to benefit from procedural simplifications?
No, they are not obliged to do so. The situation of such persons is regulated in Poland by the Law on Assistance to Ukrainian Citizens in Connection with an Armed Conflict in the Territory of Ukraine. According to it, all that is needed is to register upon arrival in Poland or apply to any municipal office no later than 60 days after arrival in Poland and obtain a PESEL (Polish acronym for „Universal Electronic System for Registration of the Population”) number.
How should a Ukrainian citizen register if they want to work and benefit from health care, daycare, etc.?
If the Ukrainian citizen, on entering Poland, was not registered by the Commander of the Border Guard checkpoint during border control, they will have to submit an application in any municipality no later than 60 days after arriving in Poland. Refugee status will not be required to take up employment or receive public benefits under the provisions of the act.
The above-mentioned Law on Assistance to Ukrainian Citizens in Connection with an Armed Conflict in the Territory of Ukraine provides for assigning PESEL numbers to Ukrainians. Applications on this matter should be submitted from 16 March 2022 in any municipality office. Consequently, the Ukrainian citizen will be able to use Polish public services (receive social assistance and medical care, take up education or establish a business).
The entire procedure of obtaining a PESEL number and a search tool allowing you to find the address of a municipal office closest to your location is available here: https://www.gov.pl/web/gov/otrymay-nomer-PESEL-ta-dovirenyy-profil-posluha-dlya-hromadyan-Ukrayiny-u-zvyazku-zi-zbroynym-konfliktom-na-terytoriyi-tsiyeyi-krayiny. The whole content is in Ukrainian.