Yes, you can apply to work with housing or dining. A lot of freshmen will work for them, I had many friends who worked in the dining halls. There are always quite a few international students working in housing/dining as well.
Whether you want to do is up to you. Most people work because they want the extra cash and save up, or they’re paying for all or part of their tuition/room&board and need a job. Working is also a good experience for after college, and it could be a valuable experience for you as an international student looking to see how an American work environment functions. However, it might be a good idea to apply for a second semester job, especially if you’re uncertain about your workload and don’t have an immediate need for a job- adjusting well to college is extremely important.
Since you haven’t been to SOAR and thus haven’t picked out any classes yet, no one can really tell you how hard the first year will be. Anyways, I thought international students have a separate SOAR from domestic students (which is why you’re going in late August)? I imagine they would reserve spots open for you guys.
It is best for all students to be able to concentrate on academics without needing to work. Of course many need to work and do so. As a foreign student new to the US as well as UW you should NOT attempt to work. I assume you can afford to attend UW. You will need time to adjust to a new culture, language, college and everything else about the US. Later, once you know the ropes, you can decide if working will interfere with your ability to take as many classes as you wish and have time to do the work required for them.
Your class load will depend on your knowledge base, ability and courses chosen. Your English skills may require certain courses- your placement tests and language test will determine those. Taking another academic class trumps any knowledge gained by doing grunt work at Res Halls- ie better to take more credits and not work.
I worked Res Halls food service back in the day, but am so glad I could take a heavy Honors load as a freshman instead of working. It was a learning experience behind the scenes working but not doing that would not have hurt me.