Your objective needs to be general, maximising and protecting wealth. At 35, it's pretty meaningless to have an objective of "40k income in retirement". So don't bother with any calculations which purport to show how you might achieve this.
Interesting. This is contrary to several sources of info I've read so far, but it does have merit, and I am a bit of a generalist by nature.
It is not about accuracy, it is about trying to ensure that you don't take on more risk than is necessary to achieve your objectives. The exercise shows that you can achieve your objectives without having to take on unnecessary risks. And so it has merit, of course you should redo the figures every so often and adjust your strategy accordingly.
Be really conscious of costs. You can keep them to an absolute minimum by buying shares directly rather than investing through ETFs. While the costs of ETFs are low, they do still eat into your returns.
In theory this is a good idea, in practice it seldom works for two reasons, firstly while most people do not have a problem identifying good companies they find it nearly impossible to determine the price they should buy at and secondly individual stocks are more volatile which often leads to people yoyo in and out of the market. With few exceptions, most people who got this route fail to track the index.
The other thing is that this is a small portfolio at this stage and so buying an ETF will achieve a good level of diversification at reasonable costs.