I think swings are necessary in my opinion. I'd get one that plugs in the wall though not a battery operated one. They're amazing. Its the first thing I bought which is funny because with my first son it was the last thing I bought he didn't get one until he was like a month or so old and I couldn't believe I didn't get him one sooner so this time it came first.
I would say a swing.
I have one that swings,glides and bounces :)
You still have a while to decide on the high chair. I mean you don't have to get that for at least 3 or 4 months after you have your baby.
And I think you have everything else your baby will NEED. Some extras would be a boppy pillow, a swing/ bouncer, etc
I have one of those high chairs and it securely fastens to the chair with two different straps. Its very safe.
My daughter is 5 minths old and we are just now starting her in the high chair. Babies dont typically sit up til about 6 months and even the high chairs thag recline dont help all that much for the way she curves when she sits. So you guys can wait and decide later on the high chair, its not too pressing right now :) honestly I could not live without her bouncy seat it creates the same swaying motion as a swing but I can control it and when shes out I can leave her in that. Shes just now getting big enough to crawl so she passes out kn the floor mid-play lol. All I used was the bassinet, bouncy seat, and a mat on the floor the first 2 1/2 months. Plus the stroller and car seat lol.