I work in year 3/4 and i think your son sounds bright. I would expect my lot to be able to do those sums written down using column addition, but they would struggle with 'holding' the numbers in their head doing it mentally. They would be capable of doing the actual sum, but wouldn't be able to remember the columns they had already done if you get what i mean.
They all struggle more with column subtraction, but again, coukd do it written down.
Times table wise, they know their 1,2,3,4,5,10,11. We were working on 6 and 8 during the summer term but it isnt quite stuck yet.
I would keep things fun for him and, like pp have said, get him some apps of maths games if you have an ipad / iphone. Get him to add up the shopping in the supermarket, add up the miles in the section of a journey, etc. Cooking and baking are always good, weighing etc. "Now if i want a cake twice the size, how much flour would i need" etc.
7+3 is easy but making those number bonds instant recall is a massive help with all maths. We do it as a quick fire round at the start of a lesson, bonds to 10, 20 and 100. It's just making sure it's really stuck in their brains.