Love your style and you've got some beautiful furniture there! A deep aubergine purple velvet on your wingbacks would look stunning. I'd tend to stick to purples in this area to keep it classy. Also, a dark purple would be more practical with kids than a cream. I'd keep the chairs you've got, unless they are really wobbly. Get someone to check them out and give you a quote for repairs and then you'll have a price to work against to see if you can get cheaper. OnePlan is right on the style and yet I don't think they look out of place in the room. I also like the idea of bench seats or if you wanted something really different, you could get a church pew?! I don't think the room has too much dark furniture as it is a large light area. Keep us posted with pics/samples of possible fabrics you find. Also, check out fabric outlet places.

I would wait for the rug, until you have the shutters up and your furniture placed..it may take on a character of its own and you'll want to compliment. My first thought though was to coordinate with your kitchen and incorporate some black, with a black/beige stripped rug, which would be fun with the wallpaper and perhaps paint your chairs black, add the shutters and you could paint the window trim black and add a large black chandelier.

I would get a better chandalier with better lighting and IMO DRs do not have to be bright as they are mostly used in the evening.

Wax is good on a dining table as easy to apply a bit more in the event of cup rings etc.