I would start by giving those cabinets a really good cleaning, including removing the knobs. Since it is a rental, I'm sure they haven't been thoroughly cleaned in quite a while. Once they are clean, reassess them. Changing the hardware will also make a big difference on them. Will this continue to be a rental? Are you expecting to get a premium price for it? Or will it be college students renting it? How it will be used will help you determine the quality of finishes to put in.

Based on these photos,I would not paint the cabs for this rental. I'd just clean them and do a quick treatment with Howard's Restore a Finish to get a bit of gleam.

It will be a rental.

forget about staining them. they are already dark. they do need a very good cleaning though. if you want to paint them (and I would since you're getting new counters and splash) then follow this link on how to paint. the main thing is the prep. with all the grime and grease on those, a thorough cleaning, sanding and priming will be necessary. Follow these instructions to the T and the cabs will look brand new. (you need new hardware)

https://www.evolutionofstyleblog.com/how-to-paint-your-kitchen-cabinets-like/

Also, I would leave that current flooring (is it marmoleum or linoleum?) It will have asbestos in it if it is. I would not rip it up and put in cheap laminate. (you also don't want that laminate in a kitchen). if you must take it out, replace w/a large tile. like a 24x24 size. less grout lines to get dirty.

I'm not goint to stain them but there are spots that need retouching so if we don't paint them we'll do a thourough cleaning and touch up.