few babies seem to have problems with taking the bottle.
The kind of bottle you chose is often a personal preference - yours and the babies. If baby doesn't seem to like the bottle, you could try a different one. I never had issues with the bottle. The teats change as baby gets older for flow but it depends on baby and the type of bottle you're using. I used Avent.

A steriliser is a good idea. You can sterilise with Milton or by boiling them in water. You don't NEED a steriliser machine as such. There are also microwave ones. I had one of those to start with. Then melted it (forgot to add water to it - OOPS!) and ended up with my electric one which I loved.

I never had a bottle warmer. I just boiled the kettle and heated them in hot water! When out and about, I'd put the formula in one of those containers with the dividers (so you can put portions in it and easily dispense) then fill 2/3 of the required water into the bottle so it was cool when needed. Then I'd top with hot water from a thermos.

In the first 6 weeks, we had around 4 bottles. After that, I had about 8 so I could have spares and not be constantly washing and sterilising if that makes sense.

good luck!