Whether you need an easel or not would mostly be dependent upon the size of painting you’ll be doing.
Smaller sizes can just be propped up on whatever you find handy or you could just lie them flat.
As far as the types of paints to use, you need to decide upon whether you want the ease of cleanup of water based paints or the longer drying time of oils.
Personally, I prefer Acrylics (water based) because they’re so much easier to use and I’m just not fond of the chemical smell of turpentine. But it’s your decision.
Also, acrylics come in varying thicknesses with tubes and jars so if you wanted an experience close to oils, you would use tube Acrylics. There are also varying thicknesses of clear gel medium to mix with the Acrylics for different effects.
Whatever you decide, DEFINITELY invest in good quality brushes and clean them and take proper care of them. If you cheap out on the brushes, you will never get the results you want and will not be happy.
If you decide on Acrylics, then you want to get nylon bristles or Taklon because natural hair brushes will swell too much from the water and will quickly be ruined. Good quality Taklon brushes can literally last a lifetime if properly cared for. I still have some which I bought about 20 or more years ago and they still work great.
Whichever medium you decide upon, you should get a good beginner book to guide you.
Also, consider water colors as you might find that appealing as well.