For all trips, I try to make sure I never have a 'single point of failure' so don't have all your information in your phone, in case it breaks, battery flat, lost or stolen.
I always have everything printed out from my outward airport parking booking, boarding pass, insurance, transfer, accomodation and insurance as I find dealing with bits of paper far easier and less faffy than finding the right screen on my phone when it needs scanning somewhere.
But the proof of funds thing is nonsense, don't worry about that.
It's always been the rule for entry from a third country into the EU, so obviously we now have to comply, coming from the UK. It's also the rule if you come to the UK from many, if not all countries.
All they want to know is that you're not going to stay in the country illegally and try to work or claim benefits. If you have a return ticket and booked accommodation, you will be absolutely fine even if you don't meet the spending money requirement, which you probably won't at a conference as you'll probably be generously fed and watered morning, noon and night.
However, if you travel to Spain, for example with a one way ticket, 50 euro in your pocket and a vague plan to sleep on a mate's sofa while you 'look for work in a bar' then you might be singled out to explain yourself.
So the moral of the story is that, if this is your plan, to book the cheapest package holiday you can find and rip up your return ticket...