You can use coconut oil on his butt, as well as for nipple cream. It's safer on cloth diapers than a lot of store bought creams, too.
We're cloth diapering (well, we're trying to, a lot of my diapers are still too big), and we're using super cheap baby washcloths as wipes. We have a warmer on my SIL's recommendation, but there's no reason we couldn't just use them cold or run one under warm water. But honestly, at $30 for the warmer, it comes to less than a couple big packs of disposable wipes - just something to consider when your finances pick back up. These are the washcloths I'm using, but you could use any kind of cloth: https://www.amazon.com/gp/product/B00GB8EMZE/ref=oh_aui_detailpage_o08_s00?ie=UTF8&psc=1
You can probably get a used baby tub for next to nothing on Craigslist, if you want one. If it's just plain plastic, it should be easy enough to sanitize.
Our hospital gave us a bulb, the leftover diapers, and that was about it for baby stuff. It seems like the bulbs are pretty universal. Our pediatrician recommends a rectal thermometer but is ok with a forehead one - presumably if we get a 100 degree reading on ours, they'd re-check rectally anyway.
I would get some kind of waterproof changing pad. It's totally worth the small expense to me, to have the protection from Mr. Poopfest ruining everything.
I'm an extremely inexperienced mom, though, so take my advice with a grain of salt