Free Standing Angled Cylinder Floor Uplight in Satin Nickel

Is this available with a round pin plug?
No, but you can remove the 3-pin plug and replace it with a 5 amp round plug.

I want a warm ambient light that gives a reasonable span of light. Will this product do the job?
If you choose the warm white lamp/bulb option this will give you the warm light you require. It takes an LED lamp of up to 6 watts and this will produce an upward light. Depending on the level it's placed depends on the light spread. It's ambient and subtle not a light that will up-light a large area but will do a nice job of illuminating a corner for example.

I want a plug in lamp like this that will be dimmable from the room light switch. Will this lamp dim if a dimmable bulb is used? If not can you recommend a floor lamp for behind furniture that will do so?
Yes no problem, use a dimmable lamp and it will do exactly what you desire.

I like these lamps and considering buying two. I would prefer to have a dimming option. Do they have this option or not?
These lamps use a GU10 base mains lamp. Dimmable lamps are readily available. You can plug this into a 3-pin 5 amp wall socket on a dimmer, or you can fit an in-line dimmer to the lead.