Adding to what you've put here. There's also 3-6% national insurance that'll be paid in top of those tax rates on income.
It's harder to file capital gains than it is income tax too though (hmrc requires evidence for cgt).
Is it possible for a normal account to receive about $ 100,000 per day, or does it need more papers?
Yes it's annual after the year (the January after normally - with the tax year ending the previous april 5th). You won't be taxed on profits (eg by the bank) until you file your tax return (and then they'll give you a link you can use to pay through).
Tax seems high when you have to pay it all at once in the January (and you're in a higher band) he might think it worthwhile at that point (or anytime after he's finished his balance sheet) to employ a tax advisor to take a look at it to see if they can find any ways to reduce taxes (if he's got all the information ready, they probably won't charge much just to check it over and offer advice).
I wouldn't know about how much you can expect to receive and transfer out of your account (and it depends on how you want to do it - you definitely won't get £100k in cash straight out of a high street bank). It'd be better to send a quick email to customer services with banks and be insist on what you actually want from them (such as: a personal account being able to transfer large sums in and out - they might give you advice you don't want or something inadequate because they think they can answer it when they don't actually know how it's handled).