hiya,
my lo is 9mo and crawling all over. He also gets impatient in his chair but is getting better and believe it or not my house, like yours, is "under construction" so is sooo not childproof!! I use the highchair before meals -like you- and drag him into the kitchen with me. my dd works from 6am and doesnt get home til 6.30/7pm most days so he also helps with dinner.
in the morning my lo has weetbix (2 of) with a little boiling water and milk.. or porridge... (sachets take 90 secs in microwave...and then i add cold milk to help it cool faster). I give him an empty suction bowl and spoon to play with while i get his breakky (and mine) ready.. I also sometimes have egg on toast... (and he has toast)... again scrambled eggs in microwave is quick. He also has baby yoghurt... which is a big hit and he'll eat it everytime.
I premake his meals when i make ours or clean up after ours... as I dont get time to do it otherwise. We are at the chunky-mashed stage of eating... and finger foods. I precook little pastas when i cook our pasta and mix up portions of say spag bol for him.. or mash up a roast etc for the next night or freeze it. Sometimes I add some extra veggies from a tin (you can get very soft diced mixed veg in tins..corn,carrot,potato and peas) it helps to make his meal chunkier and soft and easy to chew. When we eat, he has his meal first, and then we sit down to eat ours (usually much later) he has a little of what what we are eating.. to play with more than anything.
I also puree fruit and put it in ice cube trays then transfer to plastic resealable bags in freezer. I defrost a fruit block in m/wave to mix with his yog to "spice it up" for an after lunch or after dinner treat sometimes.
Slow cooked meals work really well for me. I can put it on low temp the night before or midmorning and then its ready for lo and us straight away when we want it. thats good on weekends when we get to eat together - and I'll give lo some toast with it - to keep him busy.
you're probably doing all this anyway.. but if not I hope some of this helps.