Mumsnet scares me too lol. If you want to transfer easily between cars and just make it easier to put the seat in generally then yes, I'd say Isofix bases, so make sure any travel system you get is compatible. If you are looking at dog walks etc then yeah, a bigger wheel, single at the front type is going to be more your thing. Careful about the second hand, check the car seat very carefully. Like bike helmets, if it's been dinged or been in an accident already, you don't want it. Brands I have no idea about these days sorry.
Depending on your bathroom arrangements, either a baby bath or one of those mesh type bath cradles will be useful.
Muslin cloths, brilliant things! Great for burping cloths and many other things. My Grandson even took to one as his comforter.
Depending on how you end up feeding, my daughter swore by Mam bottles that unscrew at the bottom, great for cleaning. Babies can be picky though and I ended up changing brand between 2 of mine as the last 2 would not have the ones my first 2 were happy with. Breast feeding gets more complicated and will prob be a trial and error as to what will be needed, if anything other than the boobs.
A really good bottle brush, if you use bottles. A steriliser is possible, depends if you end up with anything that needs it.
Babygrows, baby vests. Many of. Clothes? Depends if you want them. Don't bother starting with scratch mits, only get them if you need them. Baby socks arrrgh, bane of my early motherhood. Again, only get them if you want them.
Hats, yeah, you'll probably need hats. Take 2 to the hospital with you regardless of weather in in room temperature, else you'll get tutted at and potentially end up with a donated neon yellow affair that hurts your eyeballs (my niece).
Nappies, more than you will ever think you will need.
Something for your bundle of joy to sleep in. The choice is yours, as long as it has the right safety standard the super cheap will do just as well as the expensive. Unless you want fancy features.
Bepanthen/sudocreme, brilliant for everyone. Baby toiletries, your choice there.
Towels, for the child and extra, as you will find lots of new and interesting things you will need them for.
Change bag, either a special one or a bag of your choice that will fit everything in.
Change mat, not essential but you might want one.
Baby monitors, your choice if you want those.
Coffee, for you not the baby lol.
A snot clearer, nothing worse than a snotty baby that can't feed.
Temporal thermometer, might come in hand. In ear ones, though better can be tricky with a little one.
Minds gone blank now. Hopefully some ideas for you there.